I have the same problem. Will boot up and then black screen upon booting of windows. Then ezybug led GPU error on motherboard. Going back to post.
Only happening on COLD start up.
Will eventually boot fine after the 3rd time.
Gigabyte RX5600XT Gaming OC (F2 bios)
Ryzen 3600
16gb 3600hmz G.skill
MSI b450 tomahawk MAX (V3.60 bios)
Corsair RM650
EDIT: 2/6/2020
After banging my head against the wall trying to fix the crashes. I get a pretty good success rate when I first turn on the pc I hang out in the bios for a couple of minutes, I don't change anything just have the main page up. Then I exit without any changes and the PC boots up fine.
I have only had one really weird GPU error crash when I was surfing the web. But no problems with any gaming or performance. I'm acutely very happy with the performance with this card.