Sorry for bumping this thread, but I seem to be having a somewhat similar issue, so I've decided to reply here.
It is indeed correct, as deduced by sinmurv, that the bottom HDMI port has priority. But I've also noticed something else, to wit: every
second reboot, the GPU disables every port except the bottom HDMI one, and this happens regardless of whether anything is actually using said port or not. As a result, if I only have a single DisplayPort monitor plugged in, then every other time I reboot, I don't see a boot screen at all. However, I can still boot into Windows, and the affected ports start working again when the OS has fully booted.
I've experimented a bit to learn more about this issue, and here's what I've found:
- Using the latest NVIDIA graphics drivers (531.18 as of Feb 28, 2023) on Windows 11 Pro 22H2.
- Updated vBIOS with the ASUS update utility (Version V2.1).
- When first turning on the PC, the GPU always seems to prioritize DisplayPort output.
- Opening the BIOS setup screen and pressing the reset button will not change the above behavior.
- Booting into the OS and restarting the PC for the first time will also not change anything - DisplayPort still works and has priority.
- However, booting into the OS a second time and restarting the PC will cause every GPU output, except for the bottom HDMI port, to become disabled. No POST errors are thrown, and the booting process eventually completes successfully. Then all the GPU outputs start working again.
- On further restarts, the effects observed in pp. 5-6 will repeat continously. If there are two monitors, and one of them is plugged into the bottom HDMI port, then booting into the OS and restarting will cause the POST screen to appear on a different monitor each time.
Since this only happens after booting into the OS, I'm inclined to think it may be an OS/driver issue, and not a hardware issue. My normal setup involves two monitors, and one of them only has HDMI and DVI, no DisplayPort, so I can plug it into the bottom HDMI port, and use a DisplayPort for the other monitor. So for me this issue is more of a minor annoyance than a show-stopper, although I'd still like to see it resolved in the future, especially considering the price of the GPU.