Hi All!
 
tl;dr DisplayPort on the card is being a... I've recently bought a G-Sync monitor (Asus XB241H), and while it's very nice and fluid, it's only useful when it works. Today, I booted my computer and got nothing on the screen. I switched inputs a few times, rebooted a couple and got nothing. This included no BIOS output, so it's not an OS or driver issue. I ended up thinking something in linux screwed up, so I ended up completely breaking the install trying to get it to work. Somewhere along the line of breaking the install I got video back up, but it was only the text buffer, further confirming my thought that it was a Linux issue.
I then got back from uni and started a re-install. This was fine until I switched inputs to HDMI to my laptop. When I switched back to check the status of the install, I was greeted by a blank screen. Nothing I could do would bring it back. I ended up having to plug in another screen on DVI in order to see anything. Running that screen through a DP to DVI converter that does work didn't help.
 
I'm running a 970 ACX2 purchased from around the time the Witcher 3 released. It's a 04G-P4-2972-KR and has never had it's BIOS updated.
 
Is there a BIOS update or something similar? I'm reading on the Asus forums that there might be one. When I checked the version in nVidia Control Panel it looked like it was older than all of the other listed ones.

If I'm reading this correctly, it sounds like your DP cable is borked.
 
And are you using a laptop with one of those external GPU housings? If so, I'd recommend calling your laptop manufacturers customer support because those things can be VERY problematic at times.