For the last several weeks my laptop is running at 99% CPU, and have been unable to find the offending process.

Task manager shows 99%, with no one process using all the CPU, it cycles between several processes with no consistent culprit, but they only add up to about 60% anyway. If I kill tasks that are the bigger users, other tasks just rise up and start using more. Resource monitor also shows high CPU, on each processor, but nothing in the process list.

Looking at Process Explorer (running as administrator), it only reports about 2% usage. I know it's using more though as my battery life is rubbish, and the fan is constantly on.

Searching high and low, most posts point to driver interrupts, but I don't see the same symptoms, so am now stuck. I have run a full virus scan, with no alerts.

If anyone can suggest where else I should look, I would greatly appreciate the pointers.

-----------Update 1--------------

I have booted into Safe Mode (minimal), and still see full CPU in Task Manager

-----------Update 2--------------

I couldn't get to the bottom of it, so formatted and re-installed windows from scratch. That fixed it :)

Xperf trace run as admin


Task manager output Task manager

Process Explorer output Proc Explorer

Resource Monitor output Resource Monitor

closed as off-topic by psusi, Pimp Juice IT, user477799, fixer1234, Mokubai Apr 23 '17 at 7:06

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  • provide a xperf trace: pastebin.com/pgE11HRD – magicandre1981 Oct 26 '14 at 7:15
  • magicandre1981: xperf trace run as administrator can be downloaded from dropbox.com/s/ap684b7ekuv8zq2/HighCPUUsage.zip?dl=0 – BlinkyBill Oct 26 '14 at 7:24
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    @cybermonkey, no offence, but will wait for that to be clarified by a user with higher rep, before going that drasatic step. – BlinkyBill Oct 26 '14 at 7:58
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    @BlinkyBill Is there anything you remember installing/uninstalling at the time the high CPU usage started happening? How's the internet speed on the laptop, is it the expected speed or slower than expected? – AStopher Oct 26 '14 at 8:13
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    I'm voting to close this question as off-topic because the problem went away and can have no clear answer. – psusi Apr 23 '17 at 1:52

You have no CPU usage in the trace. The CPU is idle for 99%:

enter image description here

Resource Monitor shows 104% CPU usage so this is a bug and you can ignore this.

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    Not an answer.. this is better suited as a comment. – AStopher Oct 26 '14 at 7:43
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    @magicandre1981, This is the problem. Task manager and Resource monitor show 99%, while Procmon and this trace show no CPU usage. – BlinkyBill Oct 26 '14 at 7:55
  • @magicandre1981, ok I think I'm with you now. You're saying there's a bug reporting bad CPU readings in task manager/Resource Monitor, as evidenced by the 104%. – BlinkyBill Oct 26 '14 at 8:02
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    @magicandre1981, looked into CPU usage > 100%, and it looks like it has to do with CPU performance scaling, so an >100 reading is valid. More detail at superuser.com/questions/256921/…. – BlinkyBill Oct 26 '14 at 8:22

Ensure you are running Task Manager with admin rights, as it will not show processes run with administrator rights, if the user does not have administrator rights and therefore omit to show the processes which may be causing the high CPU usage.

To do this, open a CMD window with admin rights and it will show "Administrator:" in the title bar if it is run with admin rights. Then run the command taskmgr.exe


On my PC, this problem seemed to be caused by one of the Balanced power saver mode. Simply switching to High Performance or Power Saver fixed this problem for me.

Now, Task Manager shows the correct amount of CPU usage.

  • Resource Monitor says "104% Maximum Frequency". The processor is not throttling. Quite the opposite, in fact: the processor is operating at Turbo speeds. This therefore can't possibly explain the issue. – bwDraco Mar 18 '15 at 6:41

I had the same problem. Turns out a program (Steam, if you must know) was being showed incorectly. It was using up loads of CPU but the task manager reckoned it was only using 23%. Check if any program is constantly updating or performing background tasks?

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