Asrock B450 Pro4 - CSM disabled stuck on post scr.

Hey guys,

I recently changed my graphics card from an RTX 3070 to an RX 5700XT.
However, it got stuck on the "Asrock" boot screen. It froze (waited at least one hour) and prevented me from entering the BIOS using F2 or DEL. The only solution was to reset the CMOS.

When I turned on CSM, it was able to boot up normally.
Windows 11 is installed on a GPT partition in UEFI mode.


What I have tried:

- CMOS reset incl. battery (15 s)
- Downgraded BIOS to 5.00 (problem persisted)
- Updated to BIOS version to L8.02
- Deleted Windows and formated
- Tried new BIOS on Gigabyte RX 5700XT but issue remained.
- XMP disabled/no overclock

I could reinstall Windows 11 (Systeminfo shows UEFI and GPT) on an empty partition with CSM disabled.
It worked initially, but I encountered the same problem after the first update and restart.
When I switch back to my NVIDIA RTX 3070, it functions perfectly fine.
Is the UEFI of my RX 5700XT defective? Is that even possible?
Did someone experienced the same problem?

Specs:
- Ryzen 5600X
- 32GB 4x8GB 3200 MHz RAM
- 850W PSU
- Corsair H150i
- Gigabyte Gaming OC RX5700XT Rev. 1.0
- Asrock B450 Pro 4

I would be very happy to receive your answers.

I would open a support ticket with ASRock:
https://tw.asrock.com/events/tsd.asp

Be sure to include a link to this thread. Good luck