Task Manager showing incorrect CPU usage

Hi Simon,

The CPU usage depends on the programs running in the background. The CPU Utilization is the overall busyness of the system. You can check which application uses the most of your CPU on the Processes tab, then click the CPU tab to ordering it from increasing to decreasing. Can we ask for a screenshot of it?

Another is third-party programs like antivirus programs. We suggest performing a clean boot. It's for us to know if the issue will persist when running the computer on a minimal set of drivers and startup programs.

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You are not alone, I noticed this a few months ago (2017-11-17 to be honest).

I'm not sure when it started...

I have the same issue on a i7-3610QM, also a friend mine with a i7-4790.

The CPU usage show on the "Performance" tab differs from the "Details" tab.

You can use any other softwares (process explorer, process hacker, perfmon.exe, etc) to monitor the cpu usage and see the HUGE difference between the values.

I also created a small binary just to create a busy loop running on N threads.

As far I know, it should use the number of cores I set on the startup.

So my cpu has 8 cores, 100/8 = +-12.5% per core.

If I run only one thread, it says something like > 20% on the task manager performance tab.