20 is worse than 18 threads? what's wrong?

[Rid Streenger]

There is a strange problem - the same test when choosing 18 cores shows the result almost 10% higher than with 20 cores.
We ran more than once sequentially one after another, in a different order. The result does not change.

Who can tell you what the problem is and how to fix it?

[111aaa]

Maybe its due to the different clock speed?

[Rid Streenger]

No, the clock frequency does not change in both cases. Also, this is not related to parked kernels (I fixed the registry, rebooted the computer) Moreover, I launched two applications and sequentially ran the test with 18 and 20 threads - the difference is visible.