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Old 06-12-2014, 10:51 AM   #1
coralfang
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Varied cpu frequency output after overclocking


I have a desktop running archlinux mostly used for playing around with 3D stuff, so i decided to boost the cpu a little after installing a hyper 212 heatsink.

I have an amd fx 8320 clocked at 3.5Ghz, i just boosted it to 4.0GHz via the bios. The speed increase is notable.

However, the multiplier set in the bios is 4000Mhz

lscpu reads:
Code:
~ $ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                8
On-line CPU(s) list:   0-7
Thread(s) per core:    2
Core(s) per socket:    4
Socket(s):             1
Vendor ID:             AuthenticAMD
CPU family:            21
Model:                 2
Model name:            AMD FX(tm)-8320 Eight-Core Processor
Stepping:              0
CPU MHz:               1400.000
CPU max MHz:           4000.0000
CPU min MHz:           1400.0000
BogoMIPS:              8639.57
Virtualization:        AMD-V
L1d cache:             16K
L1i cache:             64K
L2 cache:              2048K
L3 cache:              8192K
Noting the "CPU max MHz" states the correct frequency as set in the bios.

When i was stressing the cpu, to see if my temperatures were stable. I used systester, which oddly shows as 4320MHz ??? Screenshot: http://imgur.com/JbutGb4

If i set the processor to use the performance governonr with cpupower, lscpu and /proc/cpuinfo show it running as 4000MHz.

I also noticed, after installing a small windows 7 partition to this machine, that some Windows tools show the processor is clocked at 4320Mhz also.

What's with the fluctutation? Bios is set to 4000MHz, some programs in both windows/linux show the cpu to be clocked at 4320MHz.

Wondering why this is. Thanks.
 
Old 06-12-2014, 02:41 PM   #2
business_kid
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In the days when you could put a 'scope on the cpu, the BIOS was always close. Those days are gone. There are so many lies in that area, and sneaky software wheezes for counting what nobody can count, that I wouldn't even guess.

I bet if you put it back to standard frequency, they will still argue.
 
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Old 06-12-2014, 06:35 PM   #3
TobiSGD
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May it be possible that you didn't disable the Turbo mode of the CPU in the BIOS. If that is the case then I have to state that systester seems to be not the proper tool to test for stability, the power envelope of a fully loaded CPU should not allow for the turbo to kick in.
Try it with Prime95/mprime instead and see if one of your cores bails out or if your temperatures go beyond sane values.
 
Old 06-13-2014, 08:46 AM   #4
coralfang
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Quote:
Originally Posted by TobiSGD View Post
May it be possible that you didn't disable the Turbo mode of the CPU in the BIOS. If that is the case then I have to state that systester seems to be not the proper tool to test for stability, the power envelope of a fully loaded CPU should not allow for the turbo to kick in.
Try it with Prime95/mprime instead and see if one of your cores bails out or if your temperatures go beyond sane values.
Yes, i disabled that. i'll try those tools and see if it makes a difference.
 
  


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