Question Why is my Asus motherboard attempting to check my monitor input setting is correct?

[HypnoticSpeck]

After so much time wasted this summer buying/exchanging components and talking to support, I've finally determined the Asus TUF Gaming Z690 and Rog Strix Z790 motherboards I was attempting to use fail to post if I don't have my monitor set to the correct input setting for the PC when I turn on my desktop PC. There appears to be a VGA check on these newer Asus motherboards I have not seen with any other Asus motherboard previously that appears to think something is disastrously wrong if the wrong input setting is selected on my monitor.

I have an Asus ProArt monitor I bought a year ago, and I am taking advantage of the multiple input options by connecting my desktop PC to the Display Port input and a Microsoft Surface Book 2 to HDMI 1. In general, I only bother to switch the input to the correct one after I've turned everything on, this has never been a problem before now to simply select the correct input after everything is on. This has worked fine in the past with multiple monitors and multiple PC's.

This summer I wanted to upgraded motherboards, so purchased the above-mentioned Asus motherboards. Everything would appear to work fine, until suddenly, my desktop PC would intermittently start frantically sounding the one long and 3 short beeps, with the white LED lighting up indicating a VGA issue. All documentation, online support articles and Asus analysts would say was that this indicates the most likely culprit to be the graphics card, with the motherboard and CPU possible culprits if reseating/replacing the graphics card did not resolve the issue. As a result, Asus direction was to buy and try different graphics cards or replace the motherboard due to possibly defective components or try out other components to verify if they were culprits.

After replacing almost all the components, even the Display Port cable, it started looking like I had fixed the issue when I suddenly got the dreaded VGA beeps again and no post. This time though, for some reason I realized I had just used the Microsoft Surface Book 2, and the Asus ProArt monitor was still set to HDMI 1. So, I switched the monitor to the Display Port input, restarted the PC, and lo and behold, the PC booted up with no post errors. Now, I have gotten the error a couple of times, but I've confirmed it's after having used the Surface, so it's definitely when the monitor is set to HDMI 1 instead of Display Port.

I've been looking for a way to turn off this VGA detect option in BIOS on my ROG Strix Z790-H Gaming WiFi motherboard, but I haven't found any documentation on this specific issue or how to fix it. I'm still not sure if I am the only person to ever have encountered this specific issue, other than others complaining about the Asus VGA check stopping their PC from booting, no one has identified the monitor input selection as the culprit. If this is a new "feature" of Asus motherboards, I can only say I am so glad they don't make other audio/video components, can one imagine if all electronics failed to start up if the correct input isn't selected on the TV and the only fix was to select the correct input, then restart the device?!

Anyone have any suggestions?

 

[Misgar]

I was forced to upgrade my old 30in Lenovo monitor to a newer 30in Dell monitor after completing a 7950X rig with an RTX 3060 GPU.

Just like you, I'm using the Display Port input on one PC and the HDMI input on an other machine.

The old Lenovo monitor would not reliably start up from the output of the RTX 3060 but was perfectly happy with the RX 580 in my 3800X and an even older GPU in a third PC. It may well have been the difference between HDMI 1.4 and HDMI 2.0, or a new DisplayPort standard. All I know is the old Lenovo wasn't happy with the new 3060.

Replacing the monitor was the easiest option for me, but I doubt you'd be happy with that solution. You might consider a quality KVM switch instead of using the monitor controls to switch between computers. Good KVMs "emuulate" a working monitor, keyboard and mouse, even when they are switched over to a different PC. This usually ensures a normal boot up into the OS, regardless of which one is using the monitor.

One of the first things the BIOS does during POST is to check for a working GPU and monitor. If the monitor is being used by another computer, the BIOS may allow the PC to boot into Windows (sometimes at a lower resolution) even though it cannot see the screen, or it may just hang because it cannot set a valid resolution and refresh rate.

Some multi-input monitors don't emulate a working input to a second PC, when another PC is currently using a different video input. Blame the monitor, blame the motherboard, it doesn't matter either way. You just don't have compatible components.

I can recommend Aten KVMs, especially the ones with a wired remote button to toggle between computer inputs. Built in monitor switches can be a bit hit and miss.

 

[HypnoticSpeck]

I was forced to upgrade my old 30in Lenovo monitor to a newer 30in Dell monitor after completing a 7950X rig with an RTX 3060 GPU.

Just like you, I'm using the Display Port input on one PC and the HDMI input on an other machine.

The old Lenovo monitor would not reliably start up from the output of the RTX 3060 but was perfectly happy with the RX 580 in my 3800X and an even older GPU in a third PC. It may well have been the difference between HDMI 1.4 and HDMI 2.0, or a new DisplayPort standard. All I know is the old Lenovo wasn't happy with the new 3060.

Replacing the monitor was the easiest option for me, but I doubt you'd be happy with that solution. You might consider a quality KVM switch instead of using the monitor controls to switch between computers. Good KVMs "emuulate" a working monitor, keyboard and mouse, even when they are switched over to a different PC. This usually ensures a normal boot up into the OS, regardless of which one is using the monitor.

One of the first things the BIOS does during POST is to check for a working GPU and monitor. If the monitor is being used by another computer, the BIOS may allow the PC to boot into Windows (sometimes at a lower resolution) even though it cannot see the screen, or it may just hang because it cannot set a valid resolution and refresh rate.

Some multi-input monitors don't emulate a working input to a second PC, when another PC is currently using a different video input. Blame the monitor, blame the motherboard, it doesn't matter either way. You just don't have compatible components.

I can recommend Aten KVMs, especially the ones with a wired remote button to toggle between computer inputs. Built in monitor switches can be a bit hit and miss.

Thanks for the detailed reply, it's good to know someone else has had and acknowledged this issue, I was beginning to think I was crazy (well, about this issue at least). I would have hoped a 2022 Asus ProArt monitor would have been compatible with a 2022/2023 Asus TUF Gaming and ROG Strix motherboard, goes back to my comment I'm glad Asus (can I at least blame them?) isn't building other AV components. I can understand old components and new technology don't always mix, but when buying new components in close phases, this shouldn't be an issue.