but an entire Mac Studio can be had for the same price that I paid for just the 3990x CPU and it got the same score as it in multithreaded Geekbench workloads and crushed it in single threaded performance.
Like you said it is quite a specific workload too right ? If it is really a fully parallel workload (and not specifically optimize on the Apple side) I imagine your CPU would still be around 3 time the performance.
Cinebench R23 (if those are actually representative),
3990x: 74,422
M1 ultra: 23,566
12700k:22,812
Geekbench
3990x: 25,166
M1 ultra: 24,055
That quite the difference in relative performance between the 2 there.