DisplayPort Boot Oddity

[jahoenigmann]

I've got a ASUS TUF X570 WiFi Plus board, and I recently changed out my GPU. When I installed the new one, my PC appeared to not post, and the board lit up the white VGA error light. I tried the GPU in a friends PC, and it worked fine. After a while of troubleshooting, my PC started working seemingly with no explanation. However, I couldn't boot to my BIOS, even with the Windows advanced restart option. It would always just boot to Windows.

 

Then today, I moved my RAM to a different slot so that they would be in dual channel (I only had it in a weird position because I just left them in whichever slots I had them when my PC finally booted), and my PC started doing the same thing. Eventually, I read something on a Steam forum post about DisplayPort potentially being the issue, and one of my two monitors is connected via DisplayPort. After unplugging the DisplayPort cable from my GPU and leaving the HDMI in, my PC immediately posted, the error light on my mother board went away, and I could actually boot to my BIOS! But then, when I plugged my DisplayPort back in and restarted my PC; it booted, but my motherboard lit up the VGA light again.

 

So, I'm curious as to what the deal is with DisplayPort. I've heard that it can be finicky, but this seems behavior seems really bizarre. Do I maybe have a bad cable?

 

 

P.S. I'm sorry if this is too vague/random/off-topic for this forum, it's my first time asking for help here.I love LTT, and I figured someone here might know something. If there's a more appropriate spot on this forum for this post, I can move it there.

[bmx6454]

i had very similar issues with the same board, using a rtx 3070. white light, and 1 long 3 short beeps(you won't have that unless you added a speaker though). for me, it ended up being an issue with the screen i was using, unplugging the screen(power cable) for a few minutes and plugging it back in worked for a while, worth a try. might be entirely different issues though. i would also try another cable if you have one handy.

[Imannudein]

Check your DisplayPort cable. It might have the DP Pin 20 problem. 

[jahoenigmann]

Thanks for the suggestions! I've got a different cable coming in today that is supposed to be VESA certified. I'll update once I try it out.

[jahoenigmann]

I was able to test the cable last night. It was a StarTech DISPLPORT6L cable that is VESA certified, per displayport.org (https://www.displayport.org/product-category/cables-adaptors/page/2/?ps=startech). I tried plugging it into my Acer EI272UR, and I still had the same issue. Then, I tried plugging the DisplayPort cable into my LG 29UB55 and running HDMI into my Acer instead, and now my pc boots properly. So the issue appeared to be something to do with Acer monitor after all lol.