(Troubleshooting) Long blackscreen before POST, sometimes not posting entirely.

Agent_HV · May 10, 2020

Hi there, I seem to have a little problem with my mainboard but I think it’s important to tell you what happened before first (you may skip this part):

Yesterday I finally got myself to do some cable management and dust cleaning on my till then working PC. Pulled any cables out, took the mainboard out, installed a backplate, put the mainboard in again, plugged any cable in in a way that it stays on its path, and closed the PC again. So far so good.
However, when I tried to turn on my PC it would just stay on the "press F2 or DEL to enter bios"-screen forever. No post, just that screen. Finally after a few attempts in which I changed nothing I got to POST, went into the BIOS, switched fast boot, and the boot logo off and proceed. But the problem persisted.

Sometimes I can get it to boot to Windows but that just happens randomly and I can’t count on a PC behaving like this when doing work.
I tried:

-Taking out the CMOS battery

-Clearing CMOS
-Plugging out any USB-stuff except mouse and keyboard (plugged them out a few times too, didn’t solve the problem)

-Testing the RAM

-Switching RAM-slots

-Plugging out every SATA drive except the boot-drive

-Only starting with APU (GPU removed)

-Putting GPU in again

-Trying to update the BIOS (failed because the newest version was already installed)

My setup:

CPU: AMD Ryzen 3 2200G

Mainboard: Asus Prime B350-Plus