CPU usage seems wrong after video board upgrade

[Joseph Stateson]

RTX-2080 was replaced under warranty with RTX-3070 (Gigabyte did not have any more 2080)
System seems to be running well but the CPU usages for CPU bound tasks shown values under %50 that were normally %99 using the gtx-1660 or rtx-2080
I removed all processors from windows 11 then rebooted but that did not fix the problem.  The win11 resource cpu plots indicate the cpu is used a lot more than the %35
Wondering if my "free" RTX-3070 was a refurbished replacement with a problem or may the problem is the express-3 motherboard with an express-4 graphics card.

[fred]

Is it a CPU or GPU task; less CPU on a GPU task is a good thing.

[Joseph Stateson]

Sorry, I cut off the image.

All those tasks in red are CPU only tasks, no GPU.  Most are now in the 20%
I have never seen CPU tasks that low
CPU time percent is set to %100

windows 11, CPU has 20 threads.

Just noticed something - I disabled GPU usage and all the CPU power levels are slowly increasing.
Went up and back down, just varying about %20 <-> %60 but should be at %99.
Going to swap the 3070 out for a 1660 and see if the problem disappears.
Will run enough CPU work units to see if the run time is really different depending on which graphics board is used.

going to run some tests using cosmology home and compare to other systems then swap out the graphics board.

[fred]

That low, maybe the CPU is doing something else with a higher priority.

[Joseph Stateson]

The problem is not the video board.  I just put the old video board back in and the problem is still there.
The problem is either the Dell bios upgrade from 206 -> 207 or the security changes to core and device protection enabled in windows 11 about the same time as that 3070 was put in.
In any event it is not caused by bointasks or tthrottle.

I went into the bios and disabled speed step and locked the CPU to the base frequency of 3.6ghz. CPU-z shows the CPUs running at 3.6.  There is no throttling and the work units for CPU bound tasks take twice as long as an older and slower Xeon.  It is as if the internal cache it not working anymore, or something is stealing the CPU cycles.

It is not permitted to downgrade the bios, will have to get with Dell support.

The %99 cpu and the almost twice as fast speed is the older Xeon. I would never have noticed this problem if I was not running boinc tasks. Windows 11 performance and resource monitoring do not show any problems.

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[fred]

The CPU % is not related to the CPU frequency or speed in any way.
It's the BOINC client counts the real time and the run time reported by Windows.
Dividing the two gives the %.
It seems that something is stealing CPU time.
Even if the cache should be disable, it still should be something close the 100%.

You should check what the load is for the individual threads and who is using them.
The resource monitor should help you with that.

[Joseph Stateson]

I found the problem and the solution.  This problem only showed up in Win11 22H2.

I cannot start BOINCTASKS first.  I have to start BOINC and then BOINGTASKS.

If I start BT first it seems there is no thread or CPU switching and the throughput drops to 2x or 3x or worse depending on how many BOINC applications are running

Discussion over at Microsoft
https://answers.microsoft.com/en-us/windows/forum/all/terrible-performance-loss-with-win11-22h2-how-to/128d232a-6b23-4c44-b2e4-56649b590e73

[edit] Problem seems related to core isolation. If I disable core isolation the cpu utilization starts increasing and within a few minutes** is back up to %90 like it should be. If core isolation is enabled then ir-regardless of the order that boinc is started the cpu utilization drops and eventually the "red" wanning shows up.

**could take a while to rise if the work unit has been running at low utilization for a long time.  However, any new tasks quickly get to %90+

[fred]

Interesting.
The sequence shouldn't matter, obviously who starts BOINC matters.

[Joseph Stateson]

I now believe this is a hardware problem of some type. The low CPU utilization reported is incorrect.  There is something different in the win11 OS causing this.

If replace the win11 boot disk with my win10 boot the CPU utilization is back to %100 as is normal.  I have the boinc apps on the D drive so whether I boot with 10 or 11 the BOINC apps pick up where they left off.

My CPU is "skylake-x" i9-7900x which has known heating problems and there are reports of "phantom throttling"

Recently I ran two CPU intensive apps.  The cpu utilization was %50 (or less) but they finished in the same time that a windows 10 comparable system finished.  I cannot run more than two or the system overheats I am considering removing the Intel heat spreader as is recommended by other skylake-x ownners.