Not sure if this will help you or not but with my Maximus XI Extreme MB and bios update I have to use a HDMI cable on my screen until I can get into bios and set up the boot area correct again to use my DP cable.
what bios are you using?
have you tried using the nvidia firmware update to see if it fixes it?
i've heard it fixes it for some while doing nothing for others.
are u plugging in the dp cable in the very left port?
there is a priority which is dp1 and dp2, same with hdmi1 and hdmi2
I'm using the latest Nvidia game-ready driver, which is version 419.35. I used a separate monitor with HDMI when I had problems getting it to load windows. so I know it's not a connection issue. I reverted back to Bios version 2012, and I'm not having any problems.
The latest bios, which is version 2203, has been problematic for my setup. I mean I could get into Windows by setting everything to default, but when overclocking, it just ends up in an endless cold boot loop.
Asus please fix this.
He is talking on firmware update for the video card it only helps some not all .... https://www.nvidia.com/object/nv-uefi-update-x64.html
I feel your pain as this this is my first ROG MB to give me the same crap with the screen never seen it before . Small trick I used when it acted up on bios 805 was just unplug the screen for a second and plug it back in and could see windows again. The crazy part is I had this video card in my Rampage Extreme V build it never did any of this crap. I got so fed up with bios 805 I got rid of it and put in bios 602 as I would sooner have a old stable bios then a bios to make more issues then it is worth. For me bios 805 mucked up the ram OC as well as my sound on desktop for my Sennheiser amplifier and headphones and made my screen act up. As soon as I put her on bios 602 my sound was fixed my OC took and no screen issues so far. So needless to say I am in no rush to try the new Bios to come out a few days ago for my MB lol. I will hold off for now until I see how people say on it.
I have the same mobo as you and i'm running 0602. I'm using dual monitors via hdmi and I get random black screens for 1-2 secs then it comes back on, only on monitor 1. Anyways, I am wanting to get new monitors 144hz, freesync and use dp. This doesn't bode well if you're having problems and it's dp and mobo related. I have no problems seeing the bios or windows with hdmi though. BTW on the original bios (before 0602) I could not see the splash screen before windows on hdmi, DVI worked fine when I used a converter. When I upgraded to 0602 it was fixed. Have you tried 0903?