# AMDFX-8350+ASUSM5A97R2 MemoryCompatibility(SolvedNotClosed)

## nlsa8z6zoz7lyih3ap

I have recently built A PC based on 

(1)  AMD FX-8350 cpu

(2)  ASUS M5A97 R2.0 mob

(3)  CORSAIR Vengeance 32GB (4 x 8GB) 240-Pin DDR3 SDRAM DDR3 1866 Desktop Memory Model CMZ32GX3M4X1866C10 

     (memory)

To the best of my knowledge, after considerable reading, these should be compatible.

However the memory fails memtest after a few hours and the PC always crashes after a few hours of compiling.

Heat is not the issue as I have set the make_opt  j=4 and this keeps the temp below 50degC.

Does anyone have any experience with this cpu and this mob?  If so can they tell me what memory has worked successfully for them?

A curious point:     The crashes stop if I disable cores 3-8 in the bios.  I can not imagine what this has to do with

the problem . It is a clue, but obviously not a solution.Last edited by nlsa8z6zoz7lyih3ap on Thu Apr 25, 2013 11:49 pm; edited 1 time in total

----------

## DONAHUE

cooling method is??

overclocking??

heating of the cpu and heating of memory each/both depend on how many cores are working

is memtest telling you anything consistent about which bank is failing?

"always crashes after a few hours of compiling." what kind of crash? anything on monitor? oops? panic? power goes off? ???

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## nlsa8z6zoz7lyih3ap

 *Quote:*   

> "always crashes after a few hours of compiling." what kind of crash? anything on monitor? oops? panic? power goes off

 

Nothing on the monitor. Sometimes the power goes off, but more frequently it just freezes and  doesn't respond to network pings.

 *Quote:*   

> is memtest telling you anything consistent about which bank is failin

 

I'm afraid that I can't answer this as I have already RMA'd the memory.

The cooling was the stock cooler, but I did keep the temp below 50degC  max while compiling by setting j<=4.

I am not currently interested in trouble shooting the situation but am interested in finding out the following:

(1) Does anyone have a working machine with this cpu,mob and memory?

(2) If anyone has a working machine with this cpu and mob, what memory are they using?

 I am really preparing myself for the eventuality that the replacement  memory doesn't work either  (Pessimistic, aren't I?)

and wondering what should I then try next? 

Many thanks for you reply and suggestions.

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## nlsa8z6zoz7lyih3ap

PS

 *Quote:*   

> is memtest telling you anything consistent about which bank is failing

 

While I didn't try memtest  on the separate memory modules, I did try them separately while compiling.

Each of the modules by itself caused a crash.

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## depontius

I'll repeat DONOHUE's question...  Are you overclocking anything?  I don't know how to equate speeds between Crucial, Newegg, etc.

Newegg indicates that things are being overclocked at 2133, but not 1866 or 1600.

Crucial recommends 1600 and offers 1866, though not as the front-line recommendation.

It would be worth double-checking, perhaps worth an experiment under-clocking, to see if that stabilizes things.

By the way, I've been interested in this board, but am afraid of UEFI.  What instructions did you use?

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## krinn

I don't remember any asus motherboard i have brought that didn't include memory module compatibility list in its manual.

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## nlsa8z6zoz7lyih3ap

 *Quote:*   

> I'll repeat DONOHUE's question... Are you overclocking anything? I don't know how to equate speeds between Crucial, Newegg, etc.

 

No. I generally used stock settings --which yielded 1333 for memory, even 'tho it is sold as 1866.  I also tested it at 1600 and 1866, with the same results.

I did no overclocking on the cpu.

 *Quote:*   

> By the way, I've been interested in this board, but am afraid of UEFI. What instructions did you use

 

The UEF| is merely an option that can be used. I chose not to use it, so from my point of view it was just like standard bios.

My pre-upgrade grub2 still worked just fine with it.  I used to always use Gigabyte mobs,  but a bit of googling caused me to worry about he "hybrid" UEFI-BIOS on their new ones.

As too the cooling method. I have an order placed for a liquid corsair cooler.  I am not interested in overclocking,

but as a retired mathematician,  I certainly would like to have 8 cores running on some of my research programmes.

The hardware has advanced so much in the last 20 years, that I am hoping to push the programmes to investigate cases that got bogged down in earlier times.

Thanks for your comments and interest.

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## nlsa8z6zoz7lyih3ap

 *Quote:*   

> I don't remember any asus motherboard i have brought that didn't include memory module compatibility list in its manual

 

Mine did too and the memory in question is on its list. 

However I am asking because searches with google yield some people who claim that not all memory compatible with an mob

will work well with all cpu's that are compatible with that mob. I know that this sounds strange, but it is for that reason

that I asked if anyone with my cpu and my mob had had success with my memory.

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## depontius

That's a much more sensible question to ask now than it would have, say more than 5 years ago.  Beginning with the Opteron and Athlon-64 families AMD moved the memory interface onto the CPU chip.  So while the motherboard is not completely divorced from memory performance, the CPU is much more the determinant than in "the old days."

In case you're not familiar with the terms, "in the old days" the CPU talked to the northbridge, and then the northbridge talked to the memory, graphics card, and PCI slots.  These days the CPU talks to the northbridge and the memory, and the northbridge talks to the PCI-express bus.  (including the graphics card(s))  Conversely, "yesterday" the southbrige talked to the rest of the peripheral chips on the motherboard, these days it pretty much sweeps them all up into one piece of silicon.  If this is stuff you already know, I apologize for being pedantic.

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## nlsa8z6zoz7lyih3ap

 *Quote:*   

>  If this is stuff you already know, I apologize for being pedantic.

 

No apologies required. In fact I enjoyed (and needed) your clear explanation.

However, if the replacement also does not work, I will be faced with the difficult question:

Which is defective, mob, memory or cpu? Or are they all  OK by themselves, but just don't fit together in some subtle way.

Thanks again for your explanation.

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## DONAHUE

waiting to fail and failing under load screams overheating to me. 

while waiting for replacement memory and/or water cooler it might be worthwhile to reseat the stock cooler with a fresh thin coat of arctic silver or shin etsu thermal grease.

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## nlsa8z6zoz7lyih3ap

 *Quote:*   

> waiting to fail and failing under load screams overheating to me

 

I certainly understand that feeling, but gkrellm (via lm_sensors) never showed temperatures over 50C when compiling, and usually they were in the high 30's or low 40's.  I may be missing something, but would the load really be high when "j=4" in /etc/make.conf? (while running emerge -eq @world)

In contrast, when running my research programmes on all 8 cores ,the temp rose to 60C within a minute, at which point I killed the process.'s. This never resulted in any crashes, but the heat generated is the reason that I have ordered the liquid cooler. 

 *Quote:*   

>   while waiting for replacement memory and/or water cooler it might be worthwhile to reseat the stock cooler with a fresh thin coat of arctic silver or shin etsu thermal grease

 

Good suggestion, but I will have the replacement memory and the water cooler before  turning it on again. Until then, I will have no memory at all in the house.

Thanks again for you comments and suggestions.

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## depontius

I'm following this with quite a bit of interest, because I'm in silicon design by day, and in about 6 months I'm planning to build a system very similar to what you're describing.  I've never had overheating problems since my old K6-3, and for that I wrote a "CPU throttler" that would read the temperature and throttle the CPU if it got too hot.  I've never gotten terribly exotic about my cooling, either.  I think that these days Linux has built-in thermal regulation - I know that the kernel has had "thermal zones" for quite a while, but don't really know how to use them.  I would suggest a little time with google and 'linux thermal zones" would give you some peace of mind.  I'm probably going to do the same.

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## Anon-E-moose

 *nlsa8z6zoz7lyih3ap wrote:*   

> I have recently built A PC based on 
> 
> (1)  AMD FX-8350 cpu
> 
> (2)  ASUS M5A97 R2.0 mob
> ...

 

It could be something as simple as the memory not getting enough voltage. 

That's something to check in the bios. 

1866 is an overclocked memory, which needs higher voltage.

The packaging or the website should tell you what the "minimum" voltage needed is.

And it may need to be bumped up a little above minimum or recommended.

Good luck.

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## nlsa8z6zoz7lyih3ap

 *Quote:*   

> . I would suggest a little time with google and 'linux thermal zones" would give you some peace of mind. 

 

Thanks for the suggestion I have already learnt lots of interesting stuff that I will use in the future.

 *Quote:*   

> It could be something as simple as the memory not getting enough voltage.
> 
> That's something to check in the bios.
> 
> 1866 is an overclocked memory, which needs higher voltage. 

 

This certainly gives me an "aha" moment. As I am not an overclocker, I had overlooked the fact that  this is promoted

as an "overclocked" memory and done nothing at all in this regard in the bios settings.  The manual shows that the bios does indeed offer such features, including a "memory tuning" feature for overclocked memories which it says takes about 5 minutes to run.  I had not not done this.  At the moment I have no memory whatsoever, but when I do, in about 2 weeks, I will report back with the results.  

Thanks again to everyone for their good comments and suggestions.

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## mattty

 *nlsa8z6zoz7lyih3ap wrote:*   

> I have recently built A PC based on 
> 
> (1)  AMD FX-8350 cpu
> 
> (2)  ASUS M5A97 R2.0 mob
> ...

 

Hi, I have exactly the same problem and partial solution. I bought the same hardware just only two RAM modules(2x8GB) the CPU and motherboard are the same. I had some talk to the seller about this problem, but they refused it saying that this CPU cannot handle such big RAM modules at the speed. I played with the system for a few days and I discovered partial solution. Setting DRAM voltage to the 1.35V(instead the 1.5V default) removed the memory failures with memtest and made the system stable. The downside of this setting is that it won't let you set RAM to more that 1600Mhz.

Hope this helps.

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## nlsa8z6zoz7lyih3ap

The replacement to the memory that I RMA'd arrived today.

Results: (1) The first of the 4 chips tested by itself showed errors on test 6 of memtest (the orignal memory failed test 5) but the second did not.

             (2) I am now running this system with the second chip  alone.  The mob only gives me 1333 Mghz with this chip.  However my PC still crashes when compiling something like gcc, unless I disable all but the first 2 cores, in bios.  However other programmes such as x264 encoding and my own mathematics programmes run just fine on all 8 cores, with the new memory.

            (3) Heat :  My Corsaire H80 liquid cooler has arrived and is now installed. While running all 8 cores at 100%, it keeps the cpu temp at  around 45C with x264 and around  50C with my own Math programmes. I also have a small fan blowing on the NorthBridge, which keeps it cool enough to touch.

Thank you, Matty, for sharing your experiences with us. 

 *Quote:*   

> Setting DRAM voltage to the 1.35V(instead the 1.5V default) removed the memory failures with memtest and made the system stable. 

 

I was able to do this with only one module installed, but with two, I was unable to boot and had to clear CMOS in bios to get up and running again.   However even with only the one module at 1.35V,  I was still unable to compile gcc or chromium without disabling all but cores 1 and 2.  Increasing memory voltage makes things worse.

So the system works, sort of, but not well enough to run "emerge" with all cores enabled, even when I set j to  2 in /etc/make.conf.   In this sense it is worse than my 4 core amd system which it is supposed to replace.

 *Quote:*   

> I had some talk to the seller about this problem, but they refused it saying that this CPU cannot handle such big RAM modules at the speed.

 

Did the seller mean that the 8GB modules are too big for the FX-8350 (I could not get them to run stably at ANY speed, no matter how slow (800mghz for ex))

If so do you know what size of modules it would support. Do you know how I could get information on what memory would run stably with this mob cpu combination.

My current Goal:   Get some advice on a 16GB memory set that would run stably with this cpu and mob.  Can anyone advise me in this regard.  I had thought that choosing memory off of the mob memory compatibility list would be enough, but apparently that is not so when the CPU is the FX-8350.  If I can't succeed in this, I will revert to my previous system.

Thanks again to everyone for their help and comments regarding my  very frustrating hardware problems.

PS  If anyone thinks that the problem is a faulty mob or cpu, I would be interested in hearing that too.

ADDED IN EDIT I no longer have confidence in my power supply. I noticed that I could smell it a bit after a full load test.  Further investigation  reveals that its fan no longer turns.   Before investigating memory any further, I shall replace the power supply. I should be able to do so in less than a week.

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## Anon-E-moose

The power supply could certainly be your problem. 

If the supply wasn't enough for the motherboard including memory, cpu, etc then you might get some of the problems you have experienced.

I was running an MSI board and was having intermittent problems that I thought were due to the age of the board

but I started having similar problems with a new board so swapped out the power supply.

Fixed all the problems, and I've tested out the old MSI board with another power supply and it works fine.

It was supplying power, but evidently not enough in certain circumstances. 

The fan dying is certainly a bad sign.

Good luck.

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## mattty

Hi,

 *Quote:*   

> Did the seller mean that the 8GB modules are too big for the FX-8350 (I could not get them to run stably at ANY speed, no matter how slow (800mghz for ex))
> 
> If so do you know what size of modules it would support. Do you know how I could get information on what memory would run stably with this mob cpu combination.

 

actually the seller's customer service was quite annoying. They just kept repeating that those AMD CPUs are unreliable and problems are common. They told me to use 2x4G modules at 1333MHz, but it is not acceptable for me. From technical point of view I do not see a reason why "big" 8G modules should be the problem. On the other hand more modules can make the situation worse.

I also tried to find some relevant supported memory list, but there are only the motherboard<->memory compatibility lists, but we would need the CPU<->memory list as the CPU talks directly to the memory.

A few more tips:

You can try setting memory timing by hand (no leaving it on auto) even when the values are the same as auto-detected. You can also check is memory timings match the XMP/SPD profile. You can display them in the BIOS/tools section.

Maybe you already now, but when the system hangs at start with red LED next to the memory lighting you can power it off by long-pressing the power button. At next start it will let you correct the settings. It remembers all the values you entered. I managed to test a lot of configurations without clearing the CMOS.

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## Kollin

Yes! Asus boards are picky when comes to memory modules!

When i bought my board ~5 years ago (m2n32ws pro) i put 8GB OCZ inside, the result was exactly the same as yours  *Quote:*   

> However the memory fails memtest after a few hours and the PC always crashes after a few hours of compiling. 

 

I spent countless hours fiddling with bios settings and memtest and finally i gave up and bought G.Skill modules. 

Since then everything works perfectly and OCZ modules are collecting dust somewhere in the drawer   :Wink: 

My advice is: Don't bother, jest get some other modules  from different manufacturer   :Wink: 

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## depontius

re: "big memory modules"

As previously mentioned, I've been spec'ing a similar system.  I tend to like to buy from Crucial.  I've been in the memory/silicon/design business for over 30 years, and I like the fact that Crucial is selling their own (Micron) memory, and can control test from wafer to DIMM.

Crucial's web site has a memory configuration tool, where you can punch in the hardware by brand/type/product and they will recommend a memory product.

What was interesting is that for this category of motherboard, "max 32G", when I tried to get ECC DIMMs they would not recommend 32G, but only 24G.  I'm presuming that from a sheer numeric point of view, 32G might be right at the top end in terms of bus loading, and when you start adding the extra chips for ECC you go over the limit.

That doesn't necessarily factor into the current discussion, other than that perhaps stuffing 32G onto one of these boards is hovering right at the edge of reliable operation.

In terms of my own plans, I don't need this machine right away, and don't want to spend the money right now.  I've been figuring that in the fall the 2nd generation Piledriver/Vishera will be out, and that sounds like a good time to pounce.  Steamroller is due next year, but I don't want to wait that long.

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## nlsa8z6zoz7lyih3ap

I have had the new PSU since Tuesday and can now report the results of testing since then.

(1)  One of the 4 memory chips. run  by itself still fails memtest at the default settings whereas the other 3 (by themselves) pass.

Therefore I am now running the PC and testing with the 3 that passed, for a total of 24GB.

In this regard note depontius comment:

 *Quote:*   

> What was interesting is that for this category of motherboard, "max 32G", when I tried to get ECC DIMMs they would not recommend 32G, but only 24G. I'm presuming that from a sheer numeric point of view, 32G might be right at the top end in terms of bus loading, and when you start adding the extra chips for ECC you go over the limit.

 

(2) I currently have this running at 1733mhz by first using the mob',s  memory overclock tuner, second choosing 1733 for the DRAM speed, and third setting the memory voltage to 1.4000 volts..

The Dram voltage change was necessary for success, and this was inspired by mattty's comment:

 *Quote:*   

>   Setting DRAM voltage to the 1.35V(instead the 1.5V default) removed the memory failures with memtest and made the system stable. The downside of this setting is that it won't let you set RAM to more that 1600Mhz.

   However I  am fortunate in getting the 1733 speed. I haven't tried 1866 yet with the new PSU, but that did pass memtest with the old PSU, so perhaps it will

with the new too. I haven't tried it yet. Of course with the old psu everything crashed under load, as mentioned earlier, so the 1866 was of no help.

(3)  The mob defaults this memory do 1333mghz although it is rated by corsaire at 1866.

(4) Regarding this main question of this thread: *Quote:*   

> .......   that not all memory compatible with an mob
> 
> will work well with all cpu's that are compatible with that mob?

 

I now believe that the answer is that the cpu does matter.  The mob manual states that *Quote:*   

> When overclocking, some amd cpu models may not support DDR3 1600 or higher frequency dimms

   The manual has other such comments as well.  While I don't overclock my cpu, the mob defaults this memory to 1333 and claims that I have overclocked it when I set it to anything higher.  All of this makes it very difficult to  choose parts and design a system from part specifications.  For that reason I am very glad to have depontius's helpful comment

 *Quote:*   

> Crucial's web site has a memory configuration tool, where you can punch in the hardware by brand/type/product and they will recommend a memory product

 

So thanks to the help of everyone who responded in this topic, I now have a fully functioning system that has not crashed in 3 days. 

While my hardware problems are solved, I think that many interesting questions remain concerning memory, mob's and cpu's.  Any further comments in this regard would be received with great interest. Thus I am going to mark this topic as solved but not closed.     

I do still have a question pertaining to my new PC ('tho it is a bit off of the memory topic.)

Question: What is the correct kernel setting for cpu type. ?    Opteron/Athlon64/Hammer/K8 comes with the advice  Select this for an AMD Opteron or Athlon64 Hammer-family processor.                                                                                                           │  

  │ Enables use of some extended instructions, and passes appropriate                                                                                                             │  

  │ optimization flags to GCC  Of course the FX-8350  doesn't look to me like and opteron or Hammer family cpu.  It doesn't even support all of the instruction set from my previous 4 core.

For that reason I have chosen  Generic-x86-64.. Does anyone know if  Opteron/Athlon64/Hammer/K8 would be a reasonable or better choice?

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## trismo

CMZ32GX3M4X1866C10(Ver3.23)(XMP) 

M5A97_R20-Memory-QVL says 4 DIMM not supportet only with 2

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## depontius

 *nlsa8z6zoz7lyih3ap wrote:*   

> 
> 
> Question: What is the correct kernel setting for cpu type. ?    Opteron/Athlon64/Hammer/K8 comes with the advice  Select this for an AMD Opteron or Athlon64 Hammer-family processor.                                                                                                           │  
> 
>   │ Enables use of some extended instructions, and passes appropriate                                                                                                             │  
> ...

 

Sadly, I know you asked for the kernel configuration, not the CFLAGS.  I suspect that for now you're probably better off with generic, as you have done.  I'm pretty sure that gcc-4.6.x won't support "-march=native" for piledriver, so here are some other references.

From the forums...

https://forums.gentoo.org/viewtopic-t-951604-start-0.html

From the Gentoo wiki - note that this is for bulldozer, not piledriver, but it's probably closer than anything else...

http://en.gentoo-wiki.com/wiki/Safe_Cflags/AMD#FX-8xxx.2F6xxx.2F4xxx_.28Bulldozer.29

From elsewhere, incidentally I believe piledriver is bdzv3...

http://www.linuxquestions.org/questions/slackware-14/trouble-compiling-gcc-and-glibc-with-piledriver-cpu-optimization-march%3Dbdver2-4175444876/

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## nlsa8z6zoz7lyih3ap

 *Quote:*   

> I'm pretty sure that gcc-4.6.x won't support "-march=native" for piledriver, so here are some other references.

 

Thanks.

That is my understanding too.  I am using gcc-4.7.2-r1. I have made complete backups of 

my installation :

(a) compiled using -mtune=generic,   and 

(b) compiled using -mtune=native.

Both of these seemed to run stably for the day that I tried them.

I am now recompiling everything using "-march-native".  I'll let you know how this works out.

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## wcg

If you are using dual-channel memory, anything over 1333mhz is overclocked

for an AMD FX cpu: http://support.amd.com/us/kbarticles/Pages/ddr3memoryfrequencyguide.aspx

(Voids the warranty, if I read the various links from that page correctly.)

I bought an M5A97, Corsair Vengeance 1866, and a Phenom II 965.

There were various problems with the motherboard (PCIe slots and

a PCIe 1.0 x16 video card scrambled the BIOS setup display,

inability to clear CMOS, the sucky ethernet chip, etc.) I ended up

RMAing it within a week and replaced it with an ASRock 990FX Extreme4,

which was compatibile with the same cpu and ram. I kept the Phenom II cpu

and Corsair 1866 ram. The ram passes memtest86 with no problems

in the ASRock board:

http://www.asrock.com/mb/AMD/990FX%20Extreme4/?cat=Specifications

(If you look at the AMD cpu-memory speed chart at the URL above,

it says 1066 is spec for a Phenom II with dual-channel memory, so that

is what it is running at. No overclocking as long as the cpu is still

under warranty. Plus it is fast enough to not be annoying at stock speeds,

and I care more about stability than peak peformance.)

That Asrock board does have a few quirks: the BIOS lies about PCIe 1.0

incompatibility when I have a PCIe 1.0 video card in the first PCIe x16

slot (maybe any of them). If I install a PCIe 1.0 video card, it gives the

AMI BIOS beep code for no video (5 beeps), and there is no post display.

But if you enter BIOS setup, the BIOS screens display just fine, it displays

the grub bootloader menu at boot, and the kernel has no problems

with the PCIe 1.0 x16 video card, in either text mode or X.

If you replace the PCIe 1.0 x16 video card with a PCIe 2.0 x16 video card,

the beeps go away, you can see the post display, and everything else

is the same. (The PCIe 2.0 card is a little faster, of course, but none of

the software that I use was hampered by the performance of the PCIe

1.0 card.)

dmesg reports one quirk:

```

QUIRK: Enable AMD PLL fix

```

I do not know whether that is a cpu quirk or a 990FX chipset quirk.

(One day I will dig into the kernel code, find that message, and find out.)

So, based on my experience, your problems are more likely with

the M5A97 than with the Corsair 1866 ram.

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## nlsa8z6zoz7lyih3ap

I am starting to suspect that I don't even understand how to read the QVL memory list.  For ex:

 *Quote:*   

> CMZ32GX3M4X1866C10(Ver3.23)(XMP)
> 
> M5A97_R20-Memory-QVL says 4 DIMM not supportet only with 2

 

Does this mean that even 'tho it is listed in the QVL as 32 GB of memory, the QVL is saying that you can only plug 2 of the 4 chips into the mob and thus use only 16GB of the 32?

That never occured to me, but now it seems as if that is what it is saying, and that I erred in purchasing this memory in the first place. Many thanks for pointing this out to me as I missed it, but would you be kind enough to confirm that this is true?

Regarding:   *Quote:*   

> What was interesting is that for this category of motherboard, "max 32G", when I tried to get ECC DIMMs they would not recommend 32G, but only 24G. I'm presuming that from a sheer numeric point of view, 32G might be right at the top end in terms of bus loading, and when you start adding the extra chips for ECC you go over the limit

 

I need some educating here  When you don't see an exact mob on the crucial memory selector web page, how does one decide what "class" an mob belongs to.

Beyond this, I am starting to get  the impression that not all mob's with the same written specs will perform as desired. If stability and performance to spec are important, how does one make a good choice?

Also   *Quote:*   

> If you are using dual-channel memory, anything over 1333mhz is overclocked
> 
> for an AMD FX cpu: http://support.amd.com/us/kbarticles/Pages/ddr3memoryfrequencyguide.aspx
> 
> (Voids the warranty, if I read the various links from that page correctly.) 

 

Thanks very much for this.   Again I am beginning to realize how poorly I understood memory specs when I chose the memory for my new PC.  Your reference and comments, and those made by others will be the basis of my attempt to read and fill in my deficiencies in this area.

Regarding my question: *Quote:*   

> Question: What is the correct kernel setting for cpu type. ? Opteron/Athlon64/Hammer/K8 comes with the advice Select this for an AMD Opteron or Athlon64 Hammer-family processor. │
> 
> │ Enables use of some extended instructions, and passes appropriate │ 

 

I have now compiled my world with gcc-4.7.2 with -march=native .   After reading https://bbs.archlinux.org/viewtopic.php?id=154333, I patched my kernel to natively support this cpu type.

Everything works stably and just fine.

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## depontius

Now to blur matters even more, toss more information into the confusion ring, etc...

I suspect the real issue here is chip density.  The drivers on the Vishera can drive so much capacitance.  Some of that capacitance is in the sockets, some is in the board traces, but what we're concerned about is the memory chip inputs.  Essentially the CPU can drive only so many memory chips.

I was not surprised to see what I did about the ECC, because ECC uses 1/9 more memory chips to store the syndrome bits.

The real question becomes, does the 8G DIMM use more chips, or denser chips than the 4G DIMM.  If it uses more chips, then the capacitive load is building up, even though it's only 2 DIMMs.

For my part, I need to email Crucial, or someone.  Because 24G can be done with 3 8G DIMMs, or with 2 8G and 2 4G.  Because pairs perform better, I would expect the latter to perform better, unless there's some sort of secret sauce in there for triplets.

This may also be a moving target, because next year there may be denser memory chips, meaning fewer needed on an 8G DIMM, and then more could be used.  Typically the input capacitance is constant, regardless of density.

(As a matter of fact, I AM a chip designer.)

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## _______0

 *depontius wrote:*   

> Now to blur matters even more, toss more information into the confusion ring, etc...
> 
> I suspect the real issue here is chip density.  The drivers on the Vishera can drive so much capacitance.  Some of that capacitance is in the sockets, some is in the board traces, but what we're concerned about is the memory chip inputs.  Essentially the CPU can drive only so many memory chips.
> 
> I was not surprised to see what I did about the ECC, because ECC uses 1/9 more memory chips to store the syndrome bits.
> ...

 

----------

## _______0

 *depontius wrote:*   

> Now to blur matters even more, toss more information into the confusion ring, etc...
> 
> I suspect the real issue here is chip density.  The drivers on the Vishera can drive so much capacitance.  Some of that capacitance is in the sockets, some is in the board traces, but what we're concerned about is the memory chip inputs.  Essentially the CPU can drive only so many memory chips.
> 
> I was not surprised to see what I did about the ECC, because ECC uses 1/9 more memory chips to store the syndrome bits.
> ...

 

non-sense, industry made sure all pieces work together and mobos advertising 32GB are supposed to work with 32GB ram. Bios stock settings should make things work. If the bios has some crazy OC section with custom values disable all or set everything to AUTO

Another trick, try to change the mem modules around.

----------

## nlsa8z6zoz7lyih3ap

 *Quote:*   

> I suspect the real issue here is chip density. The drivers on the Vishera can drive so much capacitance. Some of that capacitance is in the sockets, some is in the board traces, but what we're concerned about is the memory chip inputs. Essentially the CPU can drive only so many memory chips. 

 

Thanks so much for this.  Now I feel that I understand what is going on.  I used to make Heathkit electronics in the 1950's. In those analog days concepts such as capacitance and inductance

played the key roles; moreover   every component  in (say) a shortwave radio interacted with everything else in the kit;--the internals of one component were not entirely isolated from the others.

When I  started choosing  parts and assembling PC's about 8 years ago, I did realize that "the real world of physics" occurred inside each component , but believed (as _______0 seems to in the post above) that each component in a computer interacts with the others in a purely perfect and exact digital fashion, that the actual physics inside one component is totally hidden from all of the others.  I now no longer believe that this is true.

wcg  gave us a reference from AMD  which is well worth reading carefully and in its entirety.  (http://support.amd.com/us/kbarticles/Pages/ddr3memoryfrequencyguide.aspx).

Now all of this does make the personal selection of components for a home built PC much harder than I had realized before building this one, but perhaps not impossible. Armed with  depontius's insights, I would approach the part selection quite differently than I did before, specifically checking with the cpu manufacturer's info as well as the mob's, before choosing memory.

Regarding:

 *Quote:*   

> Bios stock settings should make things work. If the bios has some crazy OC section with custom values disable all or set everything to AUTO

 

Very good advice. However all of my problems occurred using non-overclocked stock settings.

 *Quote:*   

> Another trick, try to change the mem modules around

 

This is also very good advice. However the  2nd set of modules was tried individually (one at a time) and to-gether as sets of 3 and 4 in several different orders while doing my testing.

Regarding:

 *Quote:*   

> mobos advertising 32GB are supposed to work with 32GB ram

   This may well be true.  However as trismo kindly pointed out:

 *Quote:*   

> M5A97_R20-Memory-QVL says 4 DIMM not supportet only with 2

 

So I really goofed in my memory choice for this PC.   Although this memory comes with 4 DIMM, the mob QVL only claims that it is supported when 2 of them are used.

Curious that I could have spent so much time selecting parts and still missed something so important just because I was not looking for it.

Thanks again to everyone for their postings. I am really enjoying and benefiting from this forum topic, and encourage people to continue replying with their thoughts and knowledge regarding it.

----------

## depontius

 *_______0 wrote:*   

> 
> 
> non-sense, industry made sure all pieces work together

 

Bought any bridges lately?  I agree that the pieces all should work together, and stock BIOS settings would be the most reliable way to go.  But remember that most of these motherboards aren't engineered, they're thrown together based on the reference design(s) from the chip supplier, with some level of testing.  The amount of engineering and testing will vary widely.  The profit in the PC industry is nearly all focused on Microsoft software and Intel processors.  There are probably some other reasonably profitable components, as well.  The rest pretty much runs on a shoestring.  If you want an engineered motherboard, get a server motherboard.  Otherwise, as I said, you're getting tweaks of reference design(s).

----------

## _______0

http://support.amd.com/us/kbarticles/Pages/ddr3memoryfrequencyguide.aspx

^^^ interesting link. Good in order not to, blindly, get random stuff.

What about overclocking the RAM? I've read that's a trivial OC to easily get higher mem clock. Though I still have to try it.

----------

## nlsa8z6zoz7lyih3ap

 *Quote:*   

> What about overclocking the RAM? I've read that's a trivial OC to easily get higher mem clock. Though I still have to try it.

 

The memory I am used is rated by Corsaire as 1866,  but according to the amd link should run at 1333 with the FX-8350 cpu. (And of course I am using 3 of the 4 dimms whereas the QVL for the mob only indicates that 2 of the 4 can be used.  So in that sense anything over 1333 is overclocked.

While I am not an overclocker, I couldn't help playing with the bios settings. My partiial results are that the following run stably.

(1) Default CPU settings with 1600 for RAM with 1.35volts 

(2) Using the mob overclock tuner to set the cpu to 4320 and memory to  1439 with 1.35 volts.

As my primary interest is in a fast multiprocess stable PC,  I haven't tried much else.  

Maybe as an overclocker you would know the answer to this question:  Does over-clocking the memory actually increase performance? 

----------

## _______0

it does, and orders of magnitude.

check one of my posts back where I am testing my ram speed and somebody else does the same test but double the transfer rate. I think my post was about slow rsyncing within ram.

----------

## depontius

Going back to my post I mentioned "denser chips or more chips."  Looking at the AMD page cited, look in colums 4, 5, and 6 and you'll see some of what I was talking about, but wasn't using the right language.  "Single rank memory" means essentially that there are just enough chips to fill the 64-bit data bus.  To be honest, I don't know what configuration "standard density" is these days, so I can't tell you how many chips that comes to.  But "double rank memory" means that there are twice that many chips, and you select one rank or the other.  Double rank also means roughly twice the input capacitance on almost all signal pins.

ECC DIMMs have a 72-bit data bus instead of 64-bits.  That means 11% more chips on the DIMM.  The extra capacitance (specifically extra capacitance on the address pins) of the extra chips is why I supposed Crucial only recommended 24G on a "32G" system.  The part where I talked of using 2 8G and 2 4G DIMMs to perhaps get better performance in a 24G system would be their column 6.

Look a little further down in the "Crosshair V Formula" table and you'll see the SS/DS field.  I'm guessing that that means "Single-Sided" and "Double-Sided", meaning chips on one side of the DIMM or both sides.  At least in the past this typically corresponded to single rank and double rank, and probably does still.

The last standalone DRAM I worked on was a 16Mb SDRAM.  Since then I've been working in embedded DRAM.

----------

## Anon-E-moose

 *nlsa8z6zoz7lyih3ap wrote:*   

> (1) Default CPU settings with 1600 for RAM with 1.35volts

 

Why 1.35 volts, standard voltage is 1.5, and perhaps up to 1.55 to 1.6 for overclocking.

With that much undervolting, I would think even running at 1333 would be problematic.

You could try manually setting the memory timings to higher than spec and see if it becomes stable also.

at 1333 speed the timing should be 9-9-9-24

at 1866 it increases to 10-11-10-30

You might manually set them to 10-11-10-30 and see what they do at 1600

and it could be that the memory controller just won't handle 1600 and up speed.

----------

## wcg

So "dual rank" and "dual channel" mean different things? Interesting.

I will note that both the RMAed M5A97 and the ASRock 990FX Extreme4

autotuned the memory to 1333mhz in dual channel mode, and that

was the speed it was set at when testing with memtest86. (I downclocked

it to 1066 manually.) The Corsair 1866 was not on the QVL for the ASRock

board, but I suspected that it would work, since other speeds of Corsair

memory were there, and in fact it does work fine on that mb.

----------

## depontius

 *wcg wrote:*   

> So "dual rank" and "dual channel" mean different things? Interesting.
> 
> 

 

The data path width for a single DIMM is 64 bits - 72 bits (I think, it might be more.) for an ECC DIMM.  For "dual channel" the data path width is double that - 128 bits for the non-ECC DIMMs.  That doubles the memory bandwidth, and that is why "dual channel" is advertised as the higher-performance method.  As previously mentioned, "dual rank" essentially means two sets of chips on a DIMM, so you can get data out of one set or the other.  It doubles your memory density, but at the same performance.

----------

## wcg

 *Quote:*   

> 
> 
> Why 1.35 volts, standard voltage is 1.5, and perhaps up to 1.55 to 1.6 for overclocking.
> 
> 

 

Some dimms are rated for 1.35 volts. Examples:

Desktop:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820148660

http://www.newegg.com/Product/Product.aspx?Item=N82E16820233244

Laptop:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820148614

http://www.newegg.com/Product/Product.aspx?Item=N82E16820226344

Server:

http://www.newegg.com/Product/Product.aspx?Item=N82E16820239478

http://www.newegg.com/Product/Product.aspx?Item=N82E16820148628

----------

## Anon-E-moose

 *wcg wrote:*   

>  *Quote:*   
> 
> Why 1.35 volts, standard voltage is 1.5, and perhaps up to 1.55 to 1.6 for overclocking.
> 
>  
> ...

 

The one he mentioned isn't. 

```
    DDR3 1866

    Timing 10-11-10-30

    Cas Latency 10

    Voltage 1.5V

```

----------

## wcg

 *Quote:*   

> The one he mentioned isn't. 

 

Yes, that could cause some issues, running 1.5volt memory at 1.35volt.

----------

## wcg

I found this brief description of a "memory rank" on Wikipedia:

http://en.wikipedia.org/wiki/Memory_rank

(Attempt to see exactly what the AMD cpu table "dual rank" notation

was referring to. I can't say the picture is much clearer after reading

that and a bunch of related links there. I get the impression that

"everything is dual, quad, octal, etc rank these days", which would

make the AMD table nonsensical, as single rank dimms would be pretty

hard to find, and it does not even mention quad-rank, etc. But that is

only an impression from the way those documents are written, not

necessarily reflecting engineering reality.)

At least memtest86 tells you how wide a data path to ram your mb

is using, so you will know if you are really running in "dual channel"

mode, regardless of how the dimms are organized.

edit:

One poster on another page complained that the Wikipedia

"memory rank" page has more information on "how" than

"why" (dual ranks on the same dimm cannot be accessed

simultaneously, as they share the same data path; it is not

equivalent to "dual channel", which aggregates two N-bit

data paths to make a 2N-bit data path).

----------

## nlsa8z6zoz7lyih3ap

Performance with Different memory  speed configurations

I ran some tests to see how memory speed affects the sort of applications that I actually run on my PC.

Tests were run with the mob overclock tuner  and the choices of memory speed that it allows.

Test 1 x264 encoding

(i) 1728mghz memory

    encoded 182304 frames, 20.51 fps, 22095.24 kb/s

real    148m9.750s

user    1157m45.780s

sys     1m45.266s

(ii) 864mghz memory

   encoded 182304 frames, 20.04 fps, 22095.24 kb/s

real    151m38.255s

user    1182m20.954s

sys     2m7.435s

Comment:  In my scheme of things differences of a few % are insignificant. Thus fast memory does not appear to be important for this task.

Test 2  My own  programs concerning certain finite algebraic structures. Only type integer and operations mod 2 are used here. Structures are created in stages and stored in memory.

When new ones are created, it is necessary to retrieve the previously created ones from memory and compare them to the one currently being created.

(i) 1728 mghz memory and 8 instances of the program run simultaneously and independently with the same input

real    70m30.381s

user    69m44.433s

sys     0m1.519s

real    70m32.613s

user    69m46.014s

sys     0m1.544s

real    70m33.274s

user    69m45.189s

sys     0m1.456s

real    70m33.657s

user    69m44.019s

sys     0m1.484s

real    70m33.709s

user    69m44.682s

sys     0m1.478s

real    70m34.992s

user    69m43.341s

sys     0m1.494s

real    70m35.011s

user    69m43.182s

sys     0m1.471s

real    70m35.293s

user    69m44.040s

sys     0m1.447s

(ii) The same as the above but with only on instance run

    real    53m18.922s

user    53m13.066s

sys     0m2.064s

Comment:  We see quite strikingly that the 8 fx-8350 modules do not scale linearly whereas in previous 3GHZ 4 core phenom II they did.  However even when 8 instances are run, they compare favourably with the phenom II 4 core  which gave this result with 4 instances:

user    112m55.530s

sys     0m0.355s

real    114m8.204s

user    113m36.745s

sys     0m0.097s

real    114m36.089s

user    113m35.713s

sys     0m1.559s

real    114m54.924s

user    114m13.386s

sys     0m7.733s

Now back to the fx-8350

864  mghz memory and 8 instances of the program run simultaneously and independently with the same input

real    70m13.711s

user    69m46.721s

sys     0m2.614s

real    70m16.342s

user    69m47.318s

sys     0m2.674s

real    70m17.083s

user    69m44.463s

sys     0m2.638s

real    70m18.037s

user    69m46.672s

sys     0m2.672s

real    70m18.180s

user    69m45.355s

sys     0m2.556s

real    70m18.520s

user    69m45.227s

sys     0m2.475s

real    70m20.164s

user    69m46.312s

sys     0m2.528s                                                                                                                                                                                                    

real    70m25.131s                                                                                                                                                                                                  

user    69m44.602s

sys     0m2.549s

COMMENT: With this application,   it is also true that  memory speed has little impact on performance.  

I did numerous other tests, including ones that varied the cpu speed, and concluded that for my important applications the bottleneck  is cpu speed. I am not including the actual numbers from these additional tests here.

Of course, as has already been pointed out in this thread, there are other applications for which memory speed make a big difference.

----------

## nlsa8z6zoz7lyih3ap

 *Quote:*   

> Why 1.35 volts, standard voltage is 1.5, and perhaps up to 1.55 to 1.6 for overclocking.
> 
> 

 

This was because of matty's post earlier in this thread

 *Quote:*   

> Setting DRAM voltage to the 1.35V(instead the 1.5V default) removed the memory failures with memtest and made the system stable. The downside of this setting is that it won't let you set RAM to more that 1600Mhz. 

 

I can't give the reason why, but it works for me too. Might this have anything to do with capacitance and the fx-8350 having a "weak" memory controller?

----------

## wcg

 *Quote:*   

>  can't give the reason why, but it works for me too. Might this have anything
> 
> to do with capacitance and the fx-8350 having a "weak" memory controller?

 

That is an interesting question. I have been using the Corsair 1866 right along

at 1.5v with the Phenom II on a 990FX chipset board, no problems. I would suspect

something with the 970 chipset mb or the BIOS for it with that new cpu rather than

with the cpu itself. (CPUs do have erratas, just not on the same scale that BIOS

versions, mb revisions, and chipsets have erratas. Marketing phrases like

"new soon-to-be-released cpu ready" always seem like rank speculation

rather than fact to me. We will not really know that it was "ready" until after

a few million users have tried it with that faster cpu. If it works, all good; if not,

hope that a BIOS upgrade can fix it.)

----------

## Anon-E-moose

 *nlsa8z6zoz7lyih3ap wrote:*   

> I can't give the reason why, but it works for me too. Might this have anything to do with capacitance and the fx-8350 having a "weak" memory controller?

 

As far as the cpu memory controller and the vishera cpus in general read http://www.tomshardware.com/forum/323498-30-need-8350

My personal opinion, speed differences between 1333, 1600 and higher don't matter much, 

unless you're looking to either have spectacular benchmarks or uber-gaming performance

neither of which apply to most people with most computing needs.

As far as 1.35 vs 1.5 voltage, I would imagine that with 1.35 the timings become much looser (gives stability)

but the same could be done at 1.5 and not using auto memory timings. 

I overclock my FSB which gives me greater cpu speed, but the memory drops back to 1066 speed 

which is acceptable, to me, as the greater cpu speed makes up for the slightly slower memory access.

Bottom line do whatever works for you.

----------

## depontius

 *Anon-E-moose wrote:*   

> 
> 
> My personal opinion, speed differences between 1333, 1600 and higher don't matter much, 
> 
> unless you're looking to either have spectacular benchmarks or uber-gaming performance
> ...

 

Years back when I was building a system for my daughter's high-school graduation present, the prevailing wisdom seemed to be that you were best off running your memory at the FSB speed.  You could run it faster, but then you'd have to "slip-sync" all of the signals moving them between the two clock domains.  You would almost always lose some fraction of the higher-frequency clock interval, either grabbing controls/addresses/data from the FSB to pass to the memory, or lose some fraction of the higher-frequency clock passing data back to the FSB.  Your savings might come because the higher-frequency memory clock could count the RAS and CAS latencies with finer granularity.  (Hint - the underlying mechanisms of RAS and CAS latency are measured in nanoseconds, clock cycles are just what's available to measure that.)  The chipset FSB for her mobo was 800MHz, and that's the frequency rating of DDR2 I got her.

By the way, as for that link, I don't believe there is such a thing as "quad channel", at least not on the Vishera.  There is dual-channel, with 2 DIMMs per channel.  If it were truly quad channel, I suspect that the speed rating wouldn't drop when going from dual to quad, because all of the signals would be separate, and the only common limitation would be the power distribution on the chip.  (Though TDB-limited performance is becoming significant, these days.)

----------

## Anon-E-moose

 *depontius wrote:*   

> By the way, as for that link, I don't believe there is such a thing as "quad channel", at least not on the Vishera.  There is dual-channel, with 2 DIMMs per channel.  If it were truly quad channel, I suspect that the speed rating wouldn't drop when going from dual to quad, because all of the signals would be separate, and the only common limitation would be the power distribution on the chip.  (Though TDB-limited performance is becoming significant, these days.)

 

The vishera line was supposed to incorporate quad channel memory by adding a new memory controller.

As far as the speed drop, it would make a difference if quad channel was using a different memory controller than dual channel

and I don't know the particulars of it as I don't work at AMD, just stating an opinion.

Anyway, as I told him previously he should do what works for him, on his hardware. That's all anyone can do.

Edit to add: the memory he was using (referenced earlier in thread) is quad channel that can run as dual

but I don't know if there is a setting on the MB for one vs the other.

----------

## wcg

[edit:] (Different issues: quad rank is a potential internal dimm organization,

and I referenced it when I questioned it's omission in the AMD cpu

to memory rank/clock table; quad channel is a potential mb

dimm slot organization.) [/edit] 

("quad rank", not "quad channel")

Dram power does matter, and that probably answers any questions about

whether the dimms on the mb QVLs for inexpensive desktop mbs are likely

to be single-rank or multi-rank dimms. I stumbled on this obliquely while

browsing for any recent comments on Vishera in comp.arch:

 *Quote:*   

> 
> 
> With select DDR3 DRAM parts operating in a single-rank configuration
> 
> (point to point with no active write termination) it is possible to
> ...

 

( http://newsgroups.derkeiler.com/Archive/Comp/comp.arch/2013-05/msg00052.html )

In other words, using multi-rank dimms may fit more memory on a dimm,

but it can require 5 times as much dram power as a single-rank dimm in

operation.

(It is not only a question of "is your power supply up to it". Is the power plane

on the mb up to it, and what does it take to cool it?)

----------

## nlsa8z6zoz7lyih3ap

New Memory Installed

I checked on G. Skill's web page and used their memory finder to recommend 32GB of my memory for my mob.

They recommended: RipjawsZ ] F3-12800CL10Q-32GBZL (8Gx4)

I emailed their tech support asking if that would work on my mob with my cpu. They answered that it would work  "flawlessly."

I purchased this memory and installed it and it does indeed appear to work flawlessly.

Thanks to everyone who responded to this topic. I have learnt  a great deal from it.

Yet I am still very confused about the whole thing. (For ex memory rank is very important in performance, yet it is not clear from memory spec tables, what rank a particular memory has.)

The big question to me is this"  When picking parts to build a new PC, I start with the CPU and seek an mob and memory to go with it.  How does one do this in such a way That everything "just works."

I suppose that my advice is practical rather than theoretical.  Since the mob manufacturer looses nothing if you RMA memory, get the memory  manufacturers to recommend memory for the mob instead.

A final comment: While my system was largely stable, it was prone to crashing when I was running vmware player.  I completely cured this behaviour by replacing "-march=native"

with "-mtune=generic"    Curiously, this makes only the slightest and most insignificant of difference  in performance, with one exception:  Programs emerge notably faster now (10% I estimate) probably because gcc  has less work to do.  (I also switched my cpu type in the kernel to Processor family (Generic-x86-64) instead of using the patched kernel that supported piledriver)

Since I have spent well over a decade fussing over the best CFLAGS to use with a particular CPU, this heretical discovery has been a real shocker to me.

Programs  can still use the full instruction set  of the cpu as I have set the appropriated USE flags for that purpose.

Thanks again to everyone for their comments.

----------

