Hello. Today I build new pc and have the same problem. 5600x, B550m bazooka, 16x2 Crucial Ballistix Desktop Gaming Memory 3600 MHz, Radeon rx580.
After fresh windows install I had random reboots every minute.
Now I change ram frequency in bios to 3200 MHz and no rebooting on windows anymore. But when I run 3d mark (time spy and fire strike) I have reboot in 3 sec. after benchmark started.
Not sure if it can be PSU problem, but before I had i7 3820 with the same graphics card and PSU without any probnlems.