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When running some heavy applications like games or virtual box for some time.. the cpu usage is normal for some 15 mins and then suddently cpu usage increases. even after i quit the heavy apps and when i start some other apps, the cpu usage of the new opened application is also very high.. this continues until i reboot the system. There is no single particular process occupy more cpu. All the processes cpu usage is little high than normal.. Any solutions?

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migrated from serverfault.com Apr 14 '10 at 8:32

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What sort of differences are we talking about? How big of a change in cpu usage? –  RJFalconer Apr 11 '10 at 10:23
    
cpu usage difference is like 4 times than normal.. my firefox application take around 30-40 % of cpu time.. this occurs only after running games and heavy apps .. I have mcafee antivirus installed –  sureshbabu Apr 11 '10 at 18:06
    
it seems not to be a mcafee related problems.. even after killing all mcafee process problem remains same –  sureshbabu Apr 11 '10 at 18:51
    
I'm not 100% sure, but it could be related to a heat problem. Maybe the CPU is scaling down if it heats up. Though, would be the first time I hear about it. –  Bobby Apr 14 '10 at 8:47
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@Bobby, then you either live in a cool house (eg A/C, cold place, etc.) or you have a good system that is nicely cooled. It’s not uncommon at all. When the CPU gets hot (and from the description it sounds like it is), then it will throttle the usage from between 12.5%-87.5%. Depending on the setting and how hot it got, it could take from several seconds to several minutes for it to stop throttling and go back to running at 100%. This shows up in the Task Manager as kernel usage in the CPU graph. It should be noted however that the motherboard usually runs a siren during throttling. –  Synetech Apr 14 '10 at 12:08

3 Answers 3

up vote 2 down vote accepted

Is it possible that Intel SpeedStep or AMD's equivalent system, is throttling your CPU usage for power management. Check what power setting your computer is set to; in XP, the "portable" and the "max battery" settings will step the processor down to its lower speeds. You can use CPU-Z to see what clock speed the processor is actually running at. If your processor is running at 1.0 GHz instead of 2.6 GHz, for example, then suddenly all of the processes will be competing for a lot less power.

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what is the solution for this? –  sureshbabu Apr 28 '10 at 17:12
    
I found that using CPU-Z the core speed during the high cpu usage time is only 300-700 MHZ.. will Turning off intel speedstep resolve this issue? and power setting is set to home/office desk.. –  sureshbabu Apr 29 '10 at 1:32
    
That's odd that it is set to desk and still stepped down. It definitely sounds like your processor is being underclocked; whether that's on account of speedstep (I've never heard of it going down to 300 MHz before) or the BIOS doing it for some reason, I'm not sure. Check your processor temperature - sometimes the BIOS will clock down the proc if the temperatures are out of the safe range. You can try disabling speedstep in your BIOS - there's probably an option somewhere. –  nhinkle Apr 29 '10 at 5:28
    
I disabled speedstep in bios and in windows by setting the power scheme to "always on". The temperature also seems to very high.. speed fan shows the core * temp with some fire symbol... But in cpu-z app the core is step down to 500-900 MHZ.. dunno wat to do.. suspect that it may be hardware issue –  sureshbabu Apr 29 '10 at 5:44
    
What is the exact temperature? Also, what processor are you using? Depending on the processor, there are different peak operating temperatures. You should check that all of your system fans are running. Remove the case, then power up the computer. If you see any fans which are sitting still, that's likely your problem. –  nhinkle Apr 29 '10 at 23:36

Task Manager is only part of the picture (CPU) -- it's possible disk I/O or heavy memory usage is causing the CPU usage to spike.

You might try running Sysinternals Process Explorer to get more visibility into memory and disk I/O patterns when this occurs..

http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

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i did try using process explorer but result is same condition.. cpu usage is very high for all the processes currently running and cpu usage of new started process is very high.. I think it is a new strange virus or trojan.. –  sureshbabu Apr 18 '10 at 20:47

Or as Bobby commented, it might be a heat problem. You should install a sensor and then examine the temperature of your cpu.

Example: link text

In linux you can control the frequency of the system in /proc, how you're doing it in Windows, I don't know, maybe someone other knows something

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