Wacky problem - DP didn't work, then it did but only with HDMI now it works and I have no idea what happened.

BloopBucket · May 9, 2021

Technically already solved the issue but would like to post in case someone else had this same issue or can explain what happened. Events went as such: I step away from my computer for 10 minutes to come back to a no displayport signal message on my monitor (ASUS VG27AQ). I perform the usual trouble shooting steps, plug in HDMI, can get signal through HDMI, try power cycling the monitor, DP still doesn't work. I notice while I have both HDMI and DP plugged in they're both represented in display settings but DP connection is inactive (an aside: for those that have never seen this, in the windows display settings in the multiple displays field rather than extend or duplicate these displays turn off this display was selected. Didn't know that was a thing), I successfully switch my monitor to DP input. I then unplug the HDMI cable and the DP signal gave out again. I use my second display to try to activate the monitor again, but windows just says there's an issue with my settings configuration. I plug in the HDMI cable and I can reactivate the DP signal, I switch DP signal to my main display, switch my monitor to DP input and deactivate the HDMI signal before pulling the HDMI plug out and now everything works again. I don't know what happened, how it happened or why. The option to deactivate the display connection isn't even there anymore. Anyone got any ideas?

TL;DR fix:

1. Attach HDMI cable, switch monitor to HDMI input. Keep displayport cable attached.

2. Find display settings in windows settings, there should be a small square box that represents the DP connection, there won't be any settings available to change except multiple displays options. Switch "turn this display off" to "extend these displays"

3. Switch your monitor to displayport input.

4. In display settings, check the box to make your DP connection your main display

5. In the settings for your HDMI connection set multiple displays options from "extend these displays" to "turn this display off".

This is the esoteric ritual you must perform to solve this problem I've never heard of. Should be able to unplug your HDMI cable without issue now. I'd take pictures of my process and what I saw but then I'd have to recreate the problem which I'd rather not do. If I even can.

Note: The option may not have been worded as "turn this display off" but I can't check anymore, and the meaning is more or less the same.

v0id · May 9, 2021

Ya know this sounds similar to problems I was having when I purchased a pair of new Dell monitors, where if I used a DisplayPort cable the monitor wouldn't detect a signal until the login screen, so I couldn't enter the BIOS. HDMI worked though. Turns out I needed a firmware update (not from Geforce Experience or Windows Update) from Nvidia's website directly to make my GPU and monitor compatible. Backwards compatible my ass lol.

Here's the thread if interested

BloopBucket · May 9, 2021

11 minutes ago, v0id said:

Ya know this sounds similar to problems I was having when I purchased a pair of new Dell monitors, where if I used a DisplayPort cable the monitor wouldn't detect a signal until the login screen, so I couldn't enter the BIOS.

Had the same issue, fixed it by doing nothing for approximately 2 weeks, I seem to be good at having issues that should have never happened and fixing them in ways that should have never worked.