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4090 Strix issue: HDMI doesn't work on POST, but DP does; everything works in Windows

sinmurv
Level 7
Hello,

I think I may be missing something simple and can use some help from the Asus folks and other users here.

I have an Apex Z690/Strix 4090 OC/G.Skill 6400c32 MHz @ XMP1 rig. My PSU is a Corsair AX1600i and monitor is a G9 Neo. I am using the Asus/Nvidia stock power adapter. I am on latest vBIOS and Apex Z690 BIOS; tried CMOS reset. Windows 11, all updated. Latest Nvidia drivers. Latest GPU Tweak 3 beta (tried stables as well)

PROBLEM:
Whenever I am connected to my monitor with an HDMI cable, I get nothing during POST. If I mash DEL key and end up in BIOS, I still get nothing on screen (but can see code A9 meaning that system is in BIOS). However, windows boots just fine and I have been gaming for a couple of weeks now. The only way for me to see BIOS on my monitor is to use the DP out from the card and switch my monitor to the DP source. I want to be able to access BIOS through HDMI as well. How can I do that? (please note that I didn't have this issue using my 3090 Strix OC)

Things I have tried:
- different HDMI cables
- Maximum power set in Nvidia Control Panel
- Tried turning on/off reBAR
- Tried turning on/off CSM

I am all out of ideas, and will appreciate your wisdom here.

EDIT: familiar with JayZTwoCents video and the other thread about no video output on reboot; my issue is different.

SOLVED: solution is to swap HDMIs. The bottom HDMI port has priority. I have spent 2 hours on this. I knew it was something stupid and simple.
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6 REPLIES 6

STARRAIN_ROG
Customer Service Agent
Hi sinmurv,
Do you mean whether turn on or off CSM, the results are the same or is there any difference?
Have you tried with other monitor?
Thank you.

STARRAIN@ROG wrote:
Hi sinmurv,
Do you mean whether turn on or off CSM, the results are the same or is there any difference?
Have you tried with other monitor?
Thank you.


hello! Thank you for responding!

So I turned on CSM. First I kept it all Legacy Only, and tried several shutdown/startup cycles. Then I switched all options to UEFI only and tried again. No difference. Still A9 code but black screen. Seems like something isn't recognizing the HDMI as a legitimate source of output? I see the screen flash in cycles and then the "no HDMI Input message" comes up. However this is happening with every monitor so it is not just the G9 Neo. Again DP works fine.

Now, with HDMI, if I do not access the BIOS by mashing DEL, I see nothing during Asus ROG Splash screen and eventually end up in windows.

STARRAIN@ROG wrote:
Hi sinmurv,
Do you mean whether turn on or off CSM, the results are the same or is there any difference?
Have you tried with other monitor?
Thank you.


This has been solved. Thank you again for your input. This was a simple matter of switching HDMI plugs. The bottom HDMI port has priority. I wish this was outlined in the online manual somewhere. Again, your bottom HDMI port is the one which will be prioritized during POST for BIOS.

I have edited the top post with solution. Please mark this thread as "SOLVED".

STARRAIN_ROG
Customer Service Agent
Hi sinmurv,
Thank you for your reply and feedback.

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.

Just a small update to the above. The actual problem seems to be with the primary monitor, not with the video outputs - they all work normally, at least the HDMI ones (this is confirmed by plugging the secondary monitor into the top HDMI port instead of the bottom one; if it's the only monitor connected, it always works on every boot and reboot).

For example, when first powered on, the monitor - also an ASUS, model VG27AQL1A - displays a splash screen with the ASUS logo. If I boot up the PC while this screen is still visible, then the POST screen is shown on the secondary monitor instead. Still not sure why the monitor is not recognized by the GPU during every 2nd reboot, however. But I know for sure it did not happen with my old graphics card, so it's likely a bug in the GPU firmware.