I have a (as in factory specs) 3.6 GHz AMD FM2 A8-Series A8 5600K CPU and There is at lease 0.2 GHz difference between hardware reports in Windows and Linux.

I was tested on:

  • Win7 ultimate x64 & x86 ( both tests for 3.4 GHz )
  • Win8.1 Pro x64 & x86 ( both tests for 3.5 GHz )
  • Ubuntu 14.10 & 14.10.1 x86 & x64 (tests were right its 3.6 GHz )
  • Linux Mint 17
    • x86 & x64 Mate tested for 3.55 GHz
    • x86 & x64 Cinnamon were right for 3.6 GHz

I know the the CPU and my ASROCK motherboard available to OC (OverClock) but its not enabled so I think it does not effect on HW tests.

Anyone has an idea if its a sign for broken Hardware or just some OS stuff?

  • I can confirm that this happens on Windows 8.1. I have a Core2Quad 2.44GHZ overclocked by 15% and it shows as 2.35GHZ on Task Manager. On windows 8, the problem happened too. Dec 14, 2014 at 19:40
  • Yeah i know that windows used to 'cheat a bit' on hw info but on linux i have never noticed it. On my laptop (1.95 dualcore cpu) linux were tested 1.95 and window 1.8) Dec 14, 2014 at 19:44
  • Sadly, Windows 8 isn't perfect on this one. I don't know how a system can fail such a thing. Dec 14, 2014 at 19:55

2 Answers 2


Even without overclocking or underclocking, modern CPUs change their speed, it can enter turbo mode or it can enter power saving mode (and dip way way down). The difference in the exact background processes running is what accounts for the difference in reported speed.

In fact, for many CPU monitoring programs you can observe the changes in speed in real time as you run / close programs

  • Its true and i knew about this. I have sent back the cpu to the shop for revision and they were sent me another and told me I was right that cpu was failed. Now I have the same type and tested well on each os and teater suite. Btw win and linux still have difference (?). Dec 16, 2014 at 22:20

Would recommend something like Speccy to get accurate specifications of your PC.

Thing is Task Manger on Windows 8/8.1 always show the present clock. Sometimes when some type of power saving is enabled(especially in Laptops) the processor "Underclocks" on the go to save power and you will see a smaller number in Task Man.

  • 1
    Speccy is a great piece of software and (if I'm not mistaken) it can also save to a textfile some serialkeys Dec 14, 2014 at 19:53
  • The Windows 8 task manager doesn't ever display my CPU frequency right. My CPU is overclocked to 4.5GHz; when power saving functions are enabled, the display jumps between 1.6 and 5.5 GHz, and when disabled, it jumps between 4.46 and 4.49 GHz (in reality it is spot on 4.5).
    – ntoskrnl
    Dec 15, 2014 at 15:30
  • @ntoskrnl Check this: i.imgur.com/rKwMC0E.jpg
    – wuodland
    Dec 15, 2014 at 16:23

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