Solved: Asus Prime Z390-A Boots with VGA LED on and error code

obrien1jj · January 31, 2020

Edited 2020/01/31 0100 - A new problem and a better solution

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TLDR: Make sure your monitor is using DisplayPort version 1.2, not "1.2+HDR", just 1.2. Check the settings on the monitor itself (yes, use the little buttons on it).

Longer TLDR: the problem happened with displays plugged into the graphics card, plugging one into the motherboard too solved it, but I had to change the display's input source to the cable coming from the graphics card or it would black screen after boot. A new problem was that it thought I had 3 monitors instead of 2, so I changed the DisplayPort version my monitor was using from "1.2+HDR" to "1.2" and unplugged the cable from the motherboard and everything worked.

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The Takeaway: the Asus Prime Z390-A does not care what kind of fancy ports your GPU has, it wants an HDMI or a DisplayPort 1.2 connection on either it or the GPU, period. If you're using DisplayPort 1.2+HDR and DVI, neither of those are HDMI or DisplayPort 1.2, so you can stick an egg in your shoe and beat it.

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I don't really post much on forums and I'm new to this one, I apologize if this is in the wrong place.

I recently had to upgrade my rig because my old hardware died, and I ran into this problem. I googled it and there weren't very helpful responses, so when I solved it I decided to make a post to help anyone else with this issue. It should be noted that all my parts work, so if you're having this issue and the solution described here doesn't work, it may be that you have an issue with one or more of your parts. The bios was whatever it comes with out of the box, the chipset driver and some other drivers were updated. Specs are listed at the bottom.

Note: This particular motherboard has 4 LEDs that indicate if there's a boot issue, in addition to beep codes.

Problem1: The motherboard, out of the box, would go through the boot sequence, give 1 short beep, leave the VGA LED on, give 1 long followed by 3 short beeps, and a few seconds after my display would show the windows log-in screen, and from there everything worked fine. The VGA LED indicates a graphics card issue. From the manual:

1 short beep indicates "VGA detected, Quick boot set to disabled, No keyboard detected"
1 long followed by 3 short beeps indicates "No VGA detected"

I had a GPU plugged into the motherboard and 2 displays plugged into that GPU, Monitor1 using a DisplayPort cable, and Monitor2 using a DVI-D (Dual link) cable. No display was plugged directly into the motherboard (its rear-panel I/O).

Solution1: I plugged Monitor1 into the motherboard directly (its rear-panel I/O) using an HDMI cable, so it was now both plugged into the motherboard with an HDMI cable and into the GPU with a DisplayPort cable. After doing this, Problem1 was solved, the motherboard would boot without any extra beep codes, none of the boot LEDs stayed on, and Monitor1 would show the ASUS splash with the text telling me how to boot into the UEFI menu, but Problem2 occurred.

Problem2: The motherboard boots successfully, shows the ASUS splash screen, then black screen.

Solution2: After booting, showing the ASUS splash screen, and reaching the black screen, I changed Monitor1's input source (using the controls on the monitor itself) to DisplayPort instead of HDMI. Monitor1 then showed the windows login screen and everything worked fine.

Problem3: A new problem was that it thought I had 3 monitors instead of 2 and I had to change the input source on Monitor1 from HDMI to DisplayPort every boot so it was going through the GPU.

Solution3:

(Ok, so this probably didn't do anything because when I went back and checked again to write this, it was set back to "Auto", but to allow others to replicate my process I decided to include it)
- The first thing I did was go into the BIOS settings
  - Start computer -> Mash Delete key to enter bios -> "Advanced Mode" (bottom right) -> "Advanced" tab (upper middle) -> "System Agent (SA) Configuration" (third from top) -> "Graphics Configuration" (third from bottom) -> "Primary Display" -> change from "Auto" to "PCIE"
Then I opened the settings on Monitor1 (using the buttons on the monitor itself) and I changed the DisplayPort version it was using from "1.2+HDR" to "1.2"
- "Setting" -> "System" -> "Other Settings" -> "DisplayPort Ver."
Then I unplugged the HDMI cable from the motherboard so Monitor1 was only connected with a DisplayPort cable connecting to the GPU
Then everything worked!
- If I started the computer, it would show the ASUS splash on Monitor1, then the windows login screen on Monitor1, and it only detected 2 monitors (as it should).

I hope this helps anyone with a similar problem, this one isn't really a show-stopper, but it was annoying and it doesn't feel good to have your motherboard complaining every time it boots.

I have listed the relevant specs below: