# Is /proc/cpuinfo always accurate?

## DrSpirograph

I recently purchases a new CPU

I ordered a AMD Athlon? XP 2400+ 2.0Ghz

however, according to /proc/cpuinfo, I only have:

model name      : AMD Athlon(tm) XP 1800+

stepping        : 1

cpu MHz         : 1515.242

It's a new motherboard too, and I haven't played with any of the settings that might over or underclock it so I would've thought it would just run at the correct speed. (And even if it didn't surely the model name would still be correct)

Before I take this up with the vendor, is there any reason that cpuinfo might be reporting the wrong info?

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## Marctraider

Is the bios set correct? You must set the FSB right or the multiplier.

My cpuinfo is quite accurate, when i set my FSB lower and the clockspeed decreases, cat /proc/cpuinfo will nicely detect it, i believe the kernel detects the speed at boot, look in dmesg.

Edit: actually the model name isnt 1800+ or 2400+.

The model name is just Athlon XP, as a matter of fact, i believe that if you buy a athlonxp 1800+ 1500mhz <--- the recommended speed is 1500mhz probably, for example.

Many processors run much faster then they where 'made' for, especially with AMD's, on the other side intel doesnt like overclocking the CPU much.

It also depends on the mainboard/ram if it supports such high speeds.

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## spudicus

Check the numbers on the CPU to see if they match an AXP2400 serial (See the AMD site for what they all mean). Even if they do it could have been a rebadged AXP1800.

I don't think cpuinfo is mistaken, so I'd contact the vendor.

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## jonnevers

```

blue root # cat /proc/cpuinfo

processor       : 0

vendor_id       : AuthenticAMD

cpu family      : 6

model           : 8

model name      : AMD Athlon(tm)

stepping        : 1

cpu MHz         : 2004.410

cache size      : 256 KB

fdiv_bug        : no

hlt_bug         : no

f00f_bug        : no

coma_bug        : no

fpu             : yes

fpu_exception   : yes

cpuid level     : 1

wp              : yes

flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow

bogomips        : 3956.73

```

i  have a Athlon XP 2400+

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## garn

 *Marctraider wrote:*   

> Edit: actually the model name isnt 1800+ or 2400+.
> 
> 

 

Hrmm based off jonnevers post that looks right but on my system:

 *Quote:*   

> 
> 
> model name      : AMD Athlon(tm) XP 2100+
> 
> cpu MHz         : 1733.183
> ...

 

So maybe older XP's show the "speed" in the model name?

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## Marctraider

O well, maybe its difference between bartons and tbirds? my tbird is really 1800+ 1.5ghz but it runs at 2400+ 2ghz, while tbirds dont go that far by normal...

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## bk0

Yeah, my athlon shows the speed in the model name also:

```

processor       : 0

vendor_id       : AuthenticAMD

cpu family      : 6

model           : 10

model name      : AMD Athlon(tm) XP 2600+

stepping        : 0

cpu MHz         : 1908.887

cache size      : 512 KB

```

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## Marctraider

bk0, yours is a barton i assume?

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## spudicus

 *Marctraider wrote:*   

> bk0, yours is a barton i assume?

 

Don't the Tbirds have 256kB of cache and the Barton's 512kB cache?

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## Rainmaker

yep, my 2500 Barton runs at (only) 1833 Mhz...

(This scared the shit out of me when I first saw it   :Laughing:  )

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## bk0

 *Marctraider wrote:*   

> bk0, yours is a barton i assume?

 

Yep. I bought it as a 2.08 GHz Thoroughbred core but I'm not complaining.  :Smile: 

Doesn't the kernel get the CPU ID info directly from the processor? Unless there's some weird bug /proc/cpuinfo would have to be correct.

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## Marctraider

Directly i believe, it detects it

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## Baker

hey DrSpirograph the same thing happened to me.

I bought an AMD XP2400 a month ago and it is currently being run in a win xp box. A few weeks ago for no reason it now shows up as an 1800.

The BIOS used to display it as 2400 and now as 1800, same with the OS and 3rd party apps.

Did you contact the vendor? Did they give an explination?

Give us a follow up.

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## Marctraider

You should check the bios settings if the FSB or something else can increase.

And also for your BIOS messages, what processor does it give? if it gives you a AXP 1800+ it's obviously a wrong BIOS setting.

(Maybe it suddenly reset?)

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## MrApples

make sure the frequecy of your memory is correct to obtain standard speeds for that processor, should be 266

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## Marctraider

Mhh yes but for the other guy it just suddenly dropped back so for him that doesnt make any sence by then :)

Unless he replaced the memory or such.

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## _dook_master_

I'm hoping you guys know that even though its called a 1800+, 2500+, that it doesn't really run at that speed? Thats just a PR rating, its comparison to an equivalent Intel CPU.

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## MrApples

 *_dook_master_ wrote:*   

> I'm hoping you guys know that even though its called a 1800+, 2500+, that it doesn't really run at that speed? Thats just a PR rating, its comparison to an equivalent Intel CPU.

 

yes that was previously mentioned, but his is being misidentified

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## Marctraider

And it also matters if its a Barton or a tbird.

A Tbird 1800+ should be 1.5ghz but a barton 1800+ should be faster or slower afaik in Ghz.

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## spudicus

 *Marctraider wrote:*   

> And it also matters if its a Barton or a tbird.
> 
> A Tbird 1800+ should be 1.5ghz but a barton 1800+ should be faster or slower afaik in Ghz.

 

AMD don't make a Barton 1800+. Barton's start at 2500+:

http://www6.tomshardware.com/cpu/20030210/barton-09.html

The main difference between Palomino's, Thoroughbreds and Bartons isn't their Mhz but their FSB and Cache.

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## Marctraider

No but you could always downclock it, its more about the difference between barton and tbird. not how fast they can go ;)

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## MrApples

 *Marctraider wrote:*   

> No but you could always downclock it, its more about the difference between barton and tbird. not how fast they can go 

 

if this was a matter of underlocking i wouldnt be impressed   :Laughing: 

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## bk0

TBird is the old non-XP Athlon.

Athlon XP's are either Barton or Thoroughbred. Barton's have more L2 cache and/or faster FSB so for a given performance number they run at a lower clockspeed.

2600+ (Barton) = 1.9 GHz

2600+ (Thoroughbred) = 2.08 GHz

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## SkaMike

Here's a good link:

[url]http://139.95.253.214/SRVS/CGI-BIN/WEBCGI.EXE/,/?St=2,E=0000000000168427370,K=2025,Sxi=17,Case=obj(1224)[/url]

You should manually set your bios according to that.  Just verify the numer on your CPU with that table

+-15 or so MHz within the nominal value is accurate.  They usually very slightly.  It says my Thoroughbred 2400+ running at 2156 MHz (stable) and is a 2700+ (after overclocking).  My FSB is set at 166 and the multiplier is 13.  13 * 266 = 2158 which is close to the actual frequency.

And AMD labels their chips higher than their actual MHz.  I guess its how fast it is compared to a Pentium running at that frequency.  Although a 1800+ runs at 1533MHz, its supposedly as fast as a Pentium 1.8 GHz processor.

You can read about that here:

[url]http://139.95.253.214/SRVS/CGI-BIN/WEBCGI.EXE/,/?St=15,E=0000000000168428808,K=2025,Sxi=17,Case=obj(3511)[/url]

Sorry about the long links, I couldn't get it to work in the URL=http://... form.

Hope this helps.  :Confused: 

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## Marctraider

 *bk0 wrote:*   

> TBird is the old non-XP Athlon.
> 
> Athlon XP's are either Barton or Thoroughbred. Barton's have more L2 cache and/or faster FSB so for a given performance number they run at a lower clockspeed.
> 
> 2600+ (Barton) = 1.9 GHz
> ...

 

Oh ofcourse, i am always confused with Thoroughbred and Thunderbird (Tbird and tbred)

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## Baker

 *Marctraider wrote:*   

> And also for your BIOS messages, what processor does it give? if it gives you a AXP 1800+ it's obviously a wrong BIOS setting.
> 
> (Maybe it suddenly reset?)

 

The BIOS displays the processor type on bootup, not the speed.

For a while it was an AMD XP 2400 then it suddenly changed to AMD XP 1800 without changing any system specs or configuration

I was, and still am, really puzzled as to why this happened. I sniffed around the bios for a bit and everything was maxed out(without OCing), even reset to factory defaults.

The only thing i can think of is maybe a heating issue?

When I noticed it was running as an 1800 the temp was at 103F I later purchased some different paste and got it down to 94F

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## Marctraider

MAybe it suddenly locked ^_^

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