I've purchased a used AMD Radeon 6700 XT (reference model) and I'm trying to determine if it's defective.
If no monitors are connected then 95% of the time it will boot successfully. However, the other 5% causes the ASUS Q-Code (BIOS POST code) LED to display [AF] which means "Exit Boot Services".
I'm completely stumped and the random aspect leads to believe it's defective.
However, if a monitor is plugged in then I don't seem to ever have the problem. For example, I'm using a Linux test environment with a boot script that automatically reboots the machine after 60 seconds. This causes the machine to reboot continuously for testing. If I have no monitor plugged into the video card, it can go hours without an issue but then it will happen and freeze during the BIOS POST.
(The BIOS is updated to the latest, I've cleared the CMOS, etc.)