Ich zitiere mich mal selbst, weil der ganze Sonntag für Frickelkram draufgegangen ist:
I now had the stupidest hardware failure you can imagine and it cost me half a day. In chronological order, what I did reads like the book of horrors.
Brand new Ryzen 9 3950X on a MSI MEG X570 Godlike. Runs together with all Quadro RTX and a Geforce. After that I installed a completely new and virgin Radeon Pro W5700. Boot Loop and VGA Error, already randomly alternating. A GeForce built in, running. A RX 5500 XT built in - not running. A RX 5500 XT either. Afterwards again RTX, works. It did not run a PCIe Gen4 card from AMD. A RX Vega64 ran, a RX 580 also. Board broken? CPU defective?
Another motherboard with a R9 3900X, starts with the W5700, but only tested once. Motherboard removed, installed in the workstation together with the R9 3950X, does not work. There then the R9 3950X removed and the 3900X installed. So the same combination as with the successful start. Does not work either.
CPU defective? Motherboard defective?
Finally the original setup from this morning reassembled, GeForce in. BIOS overwritten again, not just reset. Running. RX 5700 XT in, running, RX 5500 XT in, also running. W5700 in, not running. After that the RX 5700 XT is not running anymore, the RX 5500 XT also not running. Only the Geforce... I am going in circles. BIOS flashed again. All cards are running - except the W5700, which can have AMD back. But that a graphics card causes such problems and leaves its scent mark in the BIOS, so that not a PCI Gen4 card works anymore, I never had that! And by the way: the W5700 is running on a Intel system w/o issues.
To understand my pain: both systems are water cooled with a custom loop. To merge and change components I had to move between two floors and had to mount the water cooler again and again....
What for an experience! But stolen time