r0flc0pt3r

Yes RX 580 should just work out of the box on most distros. It's drivers are very mature at this point.

What graphics card do you have? How the distro handles GPU drivers is probably the most important aspect of game performance. Usability wise, most distros are pretty similar with various degrees of hand holding. It's really just finding a desktop environment that works for you and what sort of update cycle you would prefer. Most of them will have Steam and Lutris available. Best avoid things like Debian Stable for gaming though. The software packages are soooo old. For game compatibility, check ProtonDB and Lutris.net. I personally use Arch which I quite like. Although, the install and setup is somewhat... involved. Would not recommend to a beginner. Fedora would be my second choice. It's stable and up to date. I dual boot to Windows for the rare occasion when I need it. I have Windows installed on a seperate old SSD I had and switch between them using the UEFI boot menu. I am personally not a fan on installing them both on the same drive. I've never had good luck with it.

I have the same motherboard and a HIS 5700 XT. I had this happen when I was messing around with VFIO GPU pass-through a while back. The motherboard got confused about which gpu to boot from and ended up doing neither even after I removed one, leaving a big black nothing on the screen until Linux booted. I don't know if this will work in your case but for me,I put the GPU in the top slot with 1 display cable attached. I can't remember if HDMI or Displayport made a difference. Then I reset the CMOS by turning off the power supply, removing the battery and shorting the cmos clear pins. That worked for me but I haven no idea if we are looking at the same problem. On a side note BIOS 2407 gave me RAM stability issues so I rolled back to 2204. Just keep an eye out for random crashes.