Interesting, I have the exact same issue with this board and have had it since I built my system. I looked everywhere online; this is the very first time I've found someone with the same issue. 
I don't really have a solution but here are my notes: 
I have a 13700kf and a 7900xt with 2 sticks of 6400mhz GSkill RAM. When I initially built this system I mounted my GPU vertically and that absolutely refused to boot at all. Mounting my GPU horizontally allows the system to boot, but like you, if I restart I get a black screen and no display. Through some experimentation I found that it's possible to update Windows if I just let the black screen sit for a while. Prior to that I thought I had no way of updating Windows. Also, on restart the built-in speaker beeps five times, which indicates a video error. My system is also unable to return from sleep properly. I get a black screen then too. 
I've had no real problems other than a couple of errors on booting that seemed to be random (a CMOS checksum error, and "Memory has changed!" even though it didn't).
I tried a whole bunch of BIOS settings and they didn't help.
Thanks to you I at least know that the issue is with the board and not my GPU.

SAD_GOD_GREEBA_
Interesting, I have the exact same issue with this board and have had it since I built my system. I looked everywhere online; this is the very first time I've found someone with the same issue. 
I don't really have a solution but here are my notes: 
I have a 13700kf and a 7900xt with 2 sticks of 6400mhz GSkill RAM. When I initially built this system I mounted my GPU vertically and that absolutely refused to boot at all. Mounting my GPU horizontally allows the system to boot, but like you, if I restart I get a black screen and no display. Through some experimentation I found that it's possible to update Windows if I just let the black screen sit for a while. Prior to that I thought I had no way of updating Windows. Also, on restart the built-in speaker beeps five times, which indicates a video error. My system is also unable to return from sleep properly. I get a black screen then too. 
I've had no real problems other than a couple of errors on booting that seemed to be random (a CMOS checksum error, and "Memory has changed!" even though it didn't).
I tried a whole bunch of BIOS settings and they didn't help.
Thanks to you I at least know that the issue is with the board and not my GPU.

It's interesting that your behavior is similar to the 3080ti DP issues, but you have a 7900XT. There is an nvidia firmware update for their cards that fixed it (and an evga one for theirs), but I haven't heard this on 7900XT. Any chance there's a firmware update for your monitor available?

Also, just checking, but you're not running hwinfo at startup are you? That was causing some boot errors for people (no idea why).

SAD_GOD_GREEBA, I hope you find the solution to your issue.  Also, when I first built my system, I also was running a vertical GPU mount.  I was getting so many errors and many on here helped out trying to figure it out, only to FIND out that it was a problem with the cable I was using.  That's why, when I put my GPU straight into the board, it worked.  A few months ago, I did end up getting the right cable and now I'm running a vertical GPU again, with no issues.
 
For my nieces system, my nephew believes she has the latest BIOS.  But, B0baganoosh, you mentioned updated nvidia firmware.  I can tell him to try that.  It's very weird.  

I sometimes find that it’s worth changing out the battery in the motherboard with a new one. I can always use the battery that came with it in a more easily accessible device (like AirTags) and feel changing it out and resetting the bios to defaults really helps with build stability. It really doesn’t matter brand of motherboard. After the battery is installed at the factory it’s running down even if it sits on a shelf at a warehouse for months.

13700kf / strix 4090 here, had this issue since getting a 4090 over a year ago. Mine's a Z690 dark kingpin, it doesn't stop me updating windows though, it's just an annoyance at best. Do think it's GPU related though as It never happened on my 3090 and it's the only change I've made.
 
Have tried a few different Bios, Bios settings, etc etc. Have given up. I still have a years warranty but I can live with it.
 
Boot codes normally end with 7f before the cycle restarts, which I think Is video related. Think the board hiccups and struggles to post with certain GPU's now and then, like with the Zotac cards in the past. 
 

Any updates on this?
 
I've been having the same issue since I upgraded to a 13900k along with a 7900 xtx. I did update the bios on my Z690 classified just to ensure the 13900k would work. Never had any issues with my 12700k/3080 on the same board. But dealing with the whole "no display" on restart, along with the beeps.