B350-F MB 3600 to 5800XD3
B350-F MB 3600 to 5800XD3
It's really frustrating trying to solve this problem. I'm almost ready to buy a new motherboard, but it's still puzzling. The B350F is outdated, yet it keeps causing issues.
My one suggestion would be to clear the CMOS with the 3600 installed, then make sure it POSTs, then in BIOS load the defaults there, then swap CPUs and see. Also consider that there's a small chance the CPU is bad, too. I have the same B350-F, and do plan on putting a 5x00 CPU in it at some point soon, so I might end up going through this process at some point, too.
I've already tried that too, unfortunately. It seems like there might be an issue with my BIOS—it only boots in Legacy mode. I'm out now and ordered a new one from Amazon. Hope you don't have to deal with this. Good luck!