Is there a trick to installing Proxmox VE on Gigabyte Brix with an AMD processor? I have tried several times and each time after installation, the network will not work and ip is assigned.
5800X doesn't make much sense. Got one here in the workstation and its always thermal throttling at 90 deg C (got a big 2x 120mm tower cooler) because it uses the same 142W like the 5900X and 5950X but only got one chiplet, so basically same heat but just half the surface for cooling. And the 5900X also would offer a way better bang for the buck (12 core for 400 bucks instead of 8 cores for 300).I think you should simply grab what you prefer. The difference between those both is the price...
I would probably go with 5800x if the money allows. After that probably personally 5600x, because simply newer...
But 3700x has better support in kernel 5.4 (ecc reporting)... 5600x needs kernel 5.11 to run more optimal.
However, both are good. Take the one you like and probably decide by the money you pay. Probably 3700, but with ssd raid 10 instead of ssd raid 5... (Cause you can buy one more ssd, while saved on cpu, or more ram... Both brings benefit) xD