The last time I looked the 9950x3d doesn't really work that well for this use case because it has the vcache on the first ccd. That is a problem because the linux host and most of it's programs as well as interrupts default to the first ccd and the first 1-2 cores.

Which means you get microstuttering if you pass the entire ccd into a vm, because the host will still schedule stuff on the first 1-2 cores.

You can fix this by only passing the 2nd ccd into the vm, but since it doesn't have vcache on the 9950x3d you don't get the benefits.

Another fix is to only pass the remaining cores/threads of the first ccd into the vm, but then you "only" get a 6 core/12 threads 9600x3d inside the VM.

Like your write, you could try to pin the host to use the cacheless ccd if you know your way around Linux, as you can try to juggle around irqbalance, CPUAffinity, emulatorpin, iothreadpin and isolcpus or whatever.

But the 9950x3d2 is much more comfortable in this case because it doesnt require it. If that is worth the premium is another story.

If you really want you could also game with multiple people on this, each with their own VM, one 9850x3d and the 2nd with a "9600x3d".