New motherboard fixed all my problems. Got Linux installed painlessly, got Windows setup painlessly, and now I’m just trying to find the right tweaks to get Linux to relinquish my gaming GPU properly, but that’s more Linux-fu than anything else that I"ll figure out tomorrow.
This X370 MSI Pro Carbon motherboard is great too, I should have gone with this in the first place, and it’s worth the extra $60. 7 USB ports in the back plus USB-C (no TB though), 7.1 audio jacks, 6 SATA slots. It also had both PCIE slots at 8x (16x if only one is in use) which meant I could have my Linux host GPU (RX 550) in slot 1 and put my Gaming GPU in slot 2 (so the host always starts off using the first GPU as the primary.
It’s weird that the motherboard wanted me to put the 2 sticks of RAM staggered, so if you have left to right slots 1, 2, 3, 4 it had me put them in 2 and 4. Not sure if that’s Ryzen specific or not.
Anyways, in a much better mood now :D