In my (admittedly short) research, there appear to be two different occurrences - typically "active" where it drop under heavy load ie within a game, and may drop out completely, or drop out for a few seconds and them come back - and the "non-active", where it occurs with no load occurring, or coming out of sleep, etc. The active version seems to definitely be tied to gpu/gpu drivers, but according to AMD was fixed with drivers back in mid 2020 (but maybe/maybe not?).
My issue is the latter, with the black screens occurring with no/minimal load, typically overnight when it's been sitting (but not sleeping) for a period of time. No obvious repetition - it could occur after a day or two, or could be up for a week and then do it. As mentioned, Event Viewer provides no clues. For me it started only after moving from the 3900 to the 5950 cpu.
It's funny, I actually went with the 5700XT (Powercolor) over an Nvidia at the time I built the system as I figured AMD CPU/AMD GPU...should have just stuck with nVidia. Now of course it practically impossible to find anything so I am stuck with it for time being.
Common suggested fixes seem to be...
latest gpu driver
latest gpu vbios (if available - I haven't found one for the Powercolor)
custom voltages in Adenaline software
create custom resolution instead of using built in setting
PCI-E link state power management off
Enhanced Sync OFF
Manual Tuning, set Mhz slightly above stock
Power Tuning, set to any value above 0%
Probably some others, lots of threads out there.
For me, I've loaded latest Adrenaline Driver, (no VBIOS update than I can find), latest Motherboard bios 4001, with offsets set as mention in earlier posts (although, this may not be necessary since this looks to be GPU related).
Been up for two days with no issues so far since, but as mentioned it could take up to a week before the issue occurs - part of why troubleshooting this is so frustrating. If it happens again, I'll start playing with the above suggestions I suppose, or I may just swap in the RX 570 I have and run it for a week or two and see if the issue still occurs.
meanwhile, I am on the lookout for a reasonably priced used 1080TI or 2060/2070/2080, but am not holding my breath. :(.