On a Windows 7 computer, Task Manager shows 0 CPU being used by each process in the Processes tab. Yet in the Performance tab, CPU Usage and CPU Usage History both show use over 20%.

Why is there a discrepancy, and how can one see what is utilizing the CPU?

  • Did you start task manager as administrator? – Lieven Keersmaekers Jul 24 '18 at 7:32
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    Did you check the check-box for showing processes of all users? – harrymc Jul 24 '18 at 7:41
  • @LievenKeersmaekers Great question. I started Task Manager from the Administrator account. Does that suffice, or does it still need to be explicitly started as administrator? – RockPaperLz- Mask it or Casket Jul 24 '18 at 7:48
  • That doesn't suffice no. You should see a button on the left side with a caption Show processes from all users – Lieven Keersmaekers Jul 24 '18 at 12:50

Because the task manager rounds up or rounds down the CPU usage values per process. You can see a lot of process using "0%" CPU , this is false, they use "0.xxxxxx%" CPU actually. The process manager will show more precise value to you. Some process can also be hidden (negative PID, running as another user) or some hardware may have direct access to the CPU by passing your operating system (but probably not).

Run Process Explorer and you'll see the CPU usage for everything including the process running on another Windows user.

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