Hello all,
I opened the Task Manager recently, and when I opened the CPU usage tab I noticed something odd.
I understand that the percantage of CPU usage is always 100 % minus the percentage used by the System Idle Process, right? So, for example, if the Idle process shows 95%, CPU usage is 5%.
Right now, the Idle process is using up 89%, so total CPU usage should be 100 - 89 = 11%. Yet, the total CPU usage indicator at the bottom of the Task Manager insists that the CPU usage is 34%.
Which process is using that (34-11) 23%?



Here's a Process Explorer screenshot of a very similar situation (screenshot taken a few seconds after the previous one, so the figures are slightly different, but the concept still holds):



Again, System Idle Process about 70%, other programs negligible usage... 30% unaccounted for!


And this happens all the time! There's always about 30 - 25 % CPU usage unaccounted for. Who is using the CPU?
Thanks to everyone!

Are you doing any uploading with your utorrent?

Indeed not!
uTorrent is running but quite idle. Both in terms of network bandwidth usage (I'm neither uploading nor downloading) and in terms of CPU usage (Task Manager was reporting an 1% usage, while Process Explorer was reporting zip just a few seconds later).
I just tried closing uTorrent altogether, and the figures are still the practically the same.

Thanks for your answer, btw

And no applications are running when you hit the applications Tab?

None that wouldn't also show up as processes in the processes tab! I had four Internet Explorer windows and the calculator open, and, true enough, both Task Manager and Process explorer show them open. They take up RAM, sure. But, being idle, they don't use up CPU (in fact, both Task Manager and Process Explorer read zip for CPU usage of those 4 IE windows and the calc).

In fact, what puzzles me is not that there is CPU usage per se, but rather that such usage is not attributed to any application!

As you can see, in Process Explorer's detailed list, there are several background applications running (plus the 4 foreground IE windows and the calculator) but none of them is using any CPU. So my question is, who is using that 30% and won't show up as process?

Being a Linux user so I don't have AntiSpyware,Antivrus,Windows Firewall , Microsoft Phone Home, etc.... it is hard for me to say. Could be any of the above I guess.

See just to elaborate a bit. In Linux I have what is called Htop. I use it like you would use Task manager. It tells me what EXACTLY processes are running and how much cpu they are using, EXACTLY. I can kill any at any time..So there is no confusion for me on what is taking up cpu. Maybe one of the Windows guys can tell you how to find what process is taking up that 30%.

That is strange but also the math is strange.

System Idle is not a process but simply an inverse measure of CPU usage.

If the CPU usage were indeed 34% then Sys Idle should be 66%.

Normally when running and doing nothing Sys Idle should be 99%.

See what happens if you boot into Safe Mode.

For what its worth Process Monitor will give you more info about what is running however I've yet to find it useful as it gives so much information. Task manager=not enough, process manager=too much.:bs_lame:

Also see this thread by rocky.