# Change RAM frequency in Linux?

## dj_farid

Short question:

Is it possible to somehow change the speed of RAM from within Linux?

Same question in long form:

I have a Asus K8N mainboard. Two sticks of RAM. Both sticks are PC3200, 400 MHz.

The mainboard is supposed to be able to run the memory with 400 MHz.

I had only one stick, 512 MB single sided. It worked with 400 MHz. After I bought the other stick of 1024 MB the speed went down to 333 MHz even though the BIOS is set to run it in 400 MHz.

After some research on the Asus forums, I found out that this mainboard will not run double sided RAM in 400 MHz. Single sided is no problem.

Asus blames AMD for this problem. AMD says that there is nothing in their specifications that does not permit double sided RAM.

For some reason Asus has decided not to fix this issue.

I found a little Windows utility called "A64 tweaker". This piece of software is able to change the frequency of the RAM, and a bunch of other settings.

Are there anything similar that I can do in gentoo, to raise the speed of my RAM?

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## PaulBredbury

RAM speed is under the control of the BIOS. That Windows utility is presumably changing the BIOS settings.

I would leave it at 333 - there's probably extremely little overall performance difference, whereas the difference between reliable & unreliable RAM can be very annoying, as it makes apps crash randomly in weird ways.

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## dj_farid

 *PaulBredbury wrote:*   

> RAM speed is under the control of the BIOS. That Windows utility is presumably changing the BIOS settings.

 

Yes. Probably. But the changes are not permanent. The changes disappear when I reboot the machine.

 *PaulBredbury wrote:*   

> 
> 
> I would leave it at 333 - there's probably extremely little overall performance difference, whereas the difference between reliable & unreliable RAM can be very annoying, as it makes apps crash randomly in weird ways.

 

It would not be unreliable since both the RAM and the mainboard is specified to run at these speeds.

Still my question remains unanswered.

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## dh3rm3

I have exactely the same problem on a Asus K8N-E Deluxe with an amd64 3400.

I've got two sticks of 512 Corsair DDR 3200 CAS 2.5 and I just bought a Cosair 1024 CAS 3

I can only get the three sticks to work together at 333 Mhz adjusting the CAS to 3 3 3 8 in the bios. 

As far as Asus haven't fix this issue yet, I guess we will have to go for 333 Mhz, which as Paul said isn't a real important decrease in itself as far as I can see in my system.

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## IQgryn

I'm not sure about other systems, but with my system (4 ram slots), if I use 2 sticks in striping mode (1 in each channel, I think), it knocks the speed down to 333, but if I move the second stick to the same channel (next to the first stick in my case), then it still runs at 400.  However, I haven't been able to tell a difference, even in memtest, so I think the striping overcomes the lower clock speed.

Striping mode might not be called that.  It's been awhile since I looked into it.

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## dj_farid

Yes I have read that Asus K8N Deluxe has the same problem.

My guess is that the new Corsair 1GB is double sided.

You can probably trim down the latencies a little faster than specified since the RAM is running slower than specified anyway.

I haven't tested it, but according to what I read on the Asus forum, it doesn't matter witch slots you have the RAM in.

There are older bioses that did not suffer from this problem. But those bios versions go back so far that using them you miss out on other important fixes.

I've also read that there is a gain of 5-10% of running the RAM in 400 instead of 333 MHz.

http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2330&p=3

5% is not much, but still...

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## Monkeh

 *dj_farid wrote:*   

> After some research on the Asus forums, I found out that this mainboard will not run double sided RAM in 400 MHz. Single sided is no problem.

 

It'll run double sided just fine, just not in certain configurations.

 *Quote:*   

> Asus blames AMD for this problem.

 

They're correct to.

 *Quote:*   

> AMD says that there is nothing in their specifications that does not permit double sided RAM.

 

They're right, it's not in the specs. It's a memory controller issue.

 *Quote:*   

> For some reason Asus has decided not to fix this issue.

 

Because they can't..

What you need to do is match the RAM. Two modules only, seperate channels. You should get dual-channel at DDR400 without problems, but only with a single matched pair.

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