# /proc/cpuinfo accuracy

## DigitalCorpus

I'm running a Q6700 based system. For stability reasons in my overclocking stage I settled on 3.2GHz. I had some stability issues so I bumped up teh FSB and dropped the multiplier and low and behold I've never had a crash due to my overclock. Minor problem, though mostly and annoyance, is that /proc/cpuinfo thinks I'm still using the stock multiplier of x10 and not the actual x8 so all reports say I'm running at 4GHz. I wish that were true, but for air cooling with 8GB of RAM, it isn't.

Is there anyway to fix this?

Oh, and yeah I know a G0 Q6600 would've been just as good at this stage, but I got the Q6700 for under 200 new so I couldn't pass that up.

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## rsa4046

Do you have SpeedStep enabled in spite of the OC?

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## pigeon768

What's the output from /proc/cpuinfo?

There are two fields to keep in mind: one is the 'model name' which is hardcoded for your CPU. No matter what speed your CPU is running at, the model name will always list the MHz or GHz associated with the stock CPU speed.

The other field is the 'cpu MHz' field, which is your clock speed, expressed in MHz. It is normal for this number to be a decimal - for instance, my 2GHz cpu is listed as 1993.547 MHz.

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## DigitalCorpus

rsa4046:

SpeedStep could also known as C1E or CPU Enhanced Halt in the BIOS right? Stupid question but from what I remember it is and I've always have had it on.

pigeon768:

Thanks, but I am aware of this. Here is my output and yes, I'm reading the CPU MHz. AFAIK, which isn't much in linux, the kernel wouldn't be overriding my CPU's multiplier set by the BIOS right? If it is, then I've been running at 4GHz on air cooling alone @ 1.35Vcore peaking at 64C on average, 67C on hotest core when I've assumed 3.2GHz. For sake of argument, here is my output of one CPU. not like you need to see all four?

```
processor       : 0

vendor_id       : GenuineIntel

cpu family      : 6

model           : 15

model name      : Intel(R) Core(TM)2 Quad CPU    Q6700  @ 2.66GHz

stepping        : 11

cpu MHz         : 4000.123

cache size      : 4096 KB

physical id     : 0

siblings        : 4

core id         : 0

cpu cores       : 4

apicid          : 0

initial apicid  : 0

fpu             : yes

fpu_exception   : yes

cpuid level     : 10

wp              : yes

flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm tpr_shadow vnmi flexpriority

bogomips        : 8000.24

clflush size    : 64

cache_alignment : 64

address sizes   : 36 bits physical, 48 bits virtual

power management:
```

I just took my server down to install 2 new 1.5TB HDDs since I'm running low on space (90% full!). Going to run a fsck on my root and learn the fun that should be LVM since I see a future problem if I don't switch over to it now. But all of that is off topic. Point is I have some time to experiment before I go up to full load again converting HDTV into H.264

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## DigitalCorpus

*bump*

No news? I was hoping for something.

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## Carnildo

Look at your bogomips score: that's a direct benchmark of your CPU, and on modern processors, is twice your clock speed.  You're running 4GHz.

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## DigitalCorpus

Well given that being true I find it humorously funny because I cannot even POST at 400x10! yet I've been running stable since january because the kernel kicks the x8 multiplier up to x10? Odd. If I have some time I'd like to find some benchmarks to verify this logical oddity (for me at least).

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## DigitalCorpus

bogoMIPS is wrong. It is bogus. md5sum reported 15 seconds for a 6.7GB files when running a normal 320x10 and when running 400x8 presumed as 400x10 by the kernel. Where do I file a bug report or should I try some other speedtests?

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## doctork

Perhaps that's why they call it "bogomips".  It appears to depend on the processor.

On on of my AMS X2 systems:

```
At 1000 MHz

media-x2]$grep -E 'MHz|bogo' /proc/cpuinfo

cpu MHz         : 1000.000

bogomips        : 2004.25

cpu MHz         : 1000.000

bogomips        : 2004.25

and at 2400 MHz

@media-x2]$grep -E 'MHz|bogo' /proc/cpuinfo

cpu MHz         : 2400.000

bogomips        : 4810.20

cpu MHz         : 2400.000

bogomips        : 4810.20
```

However, on a Phenom system:

```
At 1000MHz

@fino ~ $ grep -E 'MHz|bogo' /proc/cpuinfo

cpu MHz         : 1100.000

bogomips        : 4399.75

cpu MHz         : 1100.000

bogomips        : 4400.39

cpu MHz         : 1100.000

bogomips        : 4400.28

cpu MHz         : 1100.000

bogomips        : 4400.29

and at 2200 MHz

@fino ~ $ grep -E 'MHz|bogo' /proc/cpuinfo

cpu MHz         : 2200.000

bogomips        : 4399.75

cpu MHz         : 2200.000

bogomips        : 4400.39

cpu MHz         : 2200.000

bogomips        : 4400.28

cpu MHz         : 2200.000

bogomips        : 4400.29

```

Maybe Intel quads are different.

--

doc

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## DigitalCorpus

Yeah, and also the MHz is not reported correctly if you are not using the stock multiplier.

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