400% difference in CPU usage between "Task Manager" and "Sysinternal's Process Explorer"

Question

On one specific server I have 400% difference in CPU usage between "Task Manager" and "Sysinternal's Process Explorer" (both picture taken on the same screenshot, so at the exact same time).
What can be the cause of this discrepancy?

Process Explorer is ran with elevated privilege. But same result if ran as regular user.

Answer 1

the below screenshot was taken on a physical machine with 8 cores, where all cores were at 100% and cpu speed was far ahead from the base 2.2 GHz speed.

i am pretty sure of it, as there was a video encoding going on (x264 with threads=24).

this one illustrates the per core usage.

both show very wrong processxp cpu utilization.

hope this will be fixed very soon.

Answer 2

Task Manager lies about CPU usage – it scales it according to CPU throttling, meaning that if your CPU's nominal speed is 4 GHz, and it's currently throttled to 2 GHz while all cores are fully utilised, Task Manager will show 50% CPU usage, while Process Explorer will show 100% CPU usage.

Answer 3

I made a feedback in the feedback app as Microsoft only acknowledge bugs reported there! Here is the link https://aka.ms/AAlhb61 upvote it so maybe it will get microsoft attention, or made a new one I will be happy to upvote it.

Answer 4

SysInternals, or Microsoft, whoever actually maintains Process Explorer, please fix this. I used to keep Process Explorer running minimized, with its CPU usage icon in the tray. But on Windows 11 the CPU usage is so badly off that it's useless. Just earlier during a Windows Security scan it showed 11% usage, while Task Manager showed 33%. I basically stopped using it, which is a shame as it was such a nice utility.

There's also the bug where launching it at startup/logon creates a process with no window and no try icon. Either by putting a shortcut in Start menu > Startup, or by checking Process Explorer option "Run at logon". The combination of those two made me stop using it.

Answer 5

I've had the same concern for years (and as well about the same discrepancy in Task Manager between its Performance and Details tabs). And in experiencing it again today, even still on Windows 11 24h2, I dug around and found this explanation:

Task Manager’s Processes and Performance tabs now use the “% Processor Utility” counter as the basis for their CPU numbers, rather than the “% Processor Time” counter Task Manager had relied upon and that is still used by Task Manager’s Details tab and by Sysinternals Process Explorer.

It's from a helpful article which addresses this matter (with more detail) by Aaron Margosis. The italics above are mine, showing he covers both disparities. Time and closer assessment by others will confirm the accuracy, but at least for now it seems a reasonable explanation, which I thought some here may appreciate.