This is really odd

[OoChit]

Here's the thing..
My previous system 
MSI z390
9900k
WD Blue SATA SSD M.2 2280
G. Skill 32gb
Gigabyte 3080ti
Evga 1300w psu
Sound blaster Zx sound card 
Samsung odyssey g9 monitor at 240hz
System ran flawlessly 

I upgraded with
Asus tuf z390-plus wifi d4
12700k
Corsair 32gb
Everything else the same 

1. Asus wouldn't see my wd ssd. Called asus tech support.  They had to kick it up
2. I bought and installed a new samsung 2tb M.2 NVMe
3. Problem solved. Mind you, no problem on z390 board
4. Proceeded to install graphics card and sata devices
5. Installed Win11 pro
6. Graphics card covered both x1 slots. Get a riser
7. Hook up riser and sound blaster 
8. No display after turning on computer 
9. Unhook non-essential components including sound card 
10. Booted up into windows fine
11. One by one hooked up components, starting the computer after each Install 
12. Got to the sound card on riser,  no display. Then checked with a nic card, no display 
13. So I thought it might be a bad riser.  
14. To check I removed the graphics card to access the x1 slots and used onboard video. Installed sound card directly to x1 slots each,  booted to windows fine. Put riser on, booted to windows fine.
15. Left riser in, installed 3080ti, booted to windows 
16. Put either nic or sound card on riser, no display..
17. After communicating with asus via  phone I got kicked up to second level tech. Sent in my details. Waited for solution. No solution.  So I returned the board for another of the same.
18. I put together the new board on my workbench.  Fired it up with cpu,ram and ssd using onboard graphics. Then installed the sound card on x1.Looks good.
19. Installed riser, graphics card, and sata components. Installed sound card.  No problem. Booted into windows fine. Yay. Everything is good..
20. Moved the system to my desk with the g9 monitor. Hooked everything up.  No display!! Wtf? It was just working good..   The only difference was the monitor 
21. I used a smaller dell monitor on my  workbench. So i moved it over, hooked it up,  and it booted into windows just fine. 
22. I switched out displayport cables, same results
23. My conclusion: somehow my odyssey g9 monitor has a conflict with the pcie x1 lane, if there is one
24. The g9 has current firmware and software.  The asus tuf mb has current bios 

Keep in mind, my MSI z390 had zero issues. 

This is really a mystery to me
Help