I looked at your previous posts knew it nothing to do with Windows 10 and 11, it definitely hardware issue.
Saw your spec, try download older Radeon GPU driver to see if it stopped blank screens. If it still have freeze and blank screens then try install Windows Basic Display driver, if that not help then try disabled Radeon GPU in device manager and enable onboard Intel GPU in UEFI and download, install Intel HD Graphics 4600 GPU driver from device manager to see if it stop freeze and blank screens. If both Radeon and Intel GPU still has freeze and blank screens then it could be down to old PSU failing due to age.
Been here working on the computer since last post. it has been 6 hours.
It got to a point that the computer simply didn't want to turn on. My biggest fear, either psu or mobo. Not even disconnecting everything from mobo (- cpu) was doing anything, no fan spins no lights.
Ended up removing every cable, every component (-cpu, don't want to mess with my evo 212 and re-paste the cpu). With nothing but 1 fan connected to the mobo, did the wire test and psu works. Re-attached psu to mobo, it turns on. Turn off and re-add components 1 by 1 then test if it turns on, it did.
No idea why it wasn't turning on at all, but now it's back to life.
Now I'm manually installing latest windows 10 update (21h1), windows update always wanted to install 20h0, that one always failed (it prolly installed gpu drivers then after reboot blank screen). Hoping it was a 20h0 issue and 21h1 bypasses any driver issue. Atm 0 drivers installed, not even igpu (cleared it all in safe mode with ddu).
1st time having this gpu driver issue, but after googling looks like I was lucky till now, the amount of ppl with this issue + with new components...
If I get the drivers working I'll be reinstalling w11 again. Didn't have much of an issue with it during these last few days.
edit: I did try older drivers, tried installing manually instead of running setup, any option would freeze computer. Gpu is sending signal (intel still not installed), but a bit worried if it's dying.
edit2: Nope. Trying to install 21h1 nets me the same "reboot to finish installing update", I reboot pc, it does it's "30-70%" complete", then it prolly tries to install gpu drivers and bam, freezes.
I give up for today.
edit3: went to the basement, had my oold computer gathering dust, grabbed my oooold gpu (a amd hd 4830). Downloaded last available drivers, tried to install... it didn't crash, but it didn't install the display drivers (everything else got installed, catalyst, audio, among other things).
Gonna try to install latest w10 update, then check if I can install old gpu drivers.