Windows 10 not seeing virtual CPUs correctly ESXi 7.0.3

[GregChristopher]

Hi All,
     I was having serious performance issues on a VM compared to the other ones. I noticed finally that it was only showing a single CPU core in task manager.  I tried the following to try to get it to wake up and see all of the CPU cores (24; 12 CPU X 2 cores) I am trying to dedicate to it:

-Different configurations of CPUs on the host; now set at 12 CPU x 2 core
-Activation had stopped working due to migration (originally this was a physical windows system), so upgrade to windows 10 Professional to allow the hardware change to work correctly
-In device manager, uninstalling each CPU and then rebooting
-In msconfig setting the number of cpu cores, then unchecking the setting and rebooting
-Reinstalling vmware tools
-Making sure hardware version Is advanced; it's at 19

After all of these things I'm up to "2 sockets" and "2 virtual processors".

The thing that makes me think something is up in the guest software is that the device manager is seeing all of the cpus (showing 12).  It's just task manager that is only showing a limited number of cores (4 CPU graphs can be seen).
I'm running out of things to try. 

Thanks for any help.

[GregChristopher]

Well I sort of figured this out and sorry to say that Microsoft is sort of following the same policies vmware follows.

Very hard to find but looks like windows 10 "Pro" (in quotes for a reason) only supports 2 CPUs

https://codeinsecurity.wordpress.com/2022/04/07/cpu-socket-and-core-count-limits-in-windows-10-and-h...

But you can bump up the cores quite a bit.

When this was a physical machine, I was able to use all 56 cores. It really feels like some of these limits are based on the system knowing that it is virtualized.

[StephenMoll · Accepted solution]

This is correct and expected behaviour. Windows desktop operating systems have only ever supported up to 2 sockets. You can have almost as many cores per socket you want, but only 2 sockets. Generally speaking it is simpler to stick to one socket, and vary the number of cores per socket to the quantity you want. 

[GregChristopher]

Thank you!

This is sort of interesting: Since the exact image of this OS was running bare metal and had 56 cores visible, I was thrown off. But it's one socket.

when the exact image is restored as VM it only sees the 2 (max; 1 if activation is broken) and of course we are limited to 2 cores per socket in HW v19 so 4 total.