ROG STRIX Z790-A GAMING WIFI II - BIOS Bug? VGA not detect at x16

[De1222]

Hello.
You will not believe me if I tell you what problem I ran into. SYSTEM SPEC:

14700K - EVGA 3080Ti XC3 - 2x32GB 6600 Corsair Titanium - 2TB 990 Pro

My graphics card does not recognize the mentioned motherboard. I have fairly good experience in DIY PC and troubleshooting plus having a good amount of spare parts for testing.
This system works with 6900XT and Quadro P400 graphics without any problems. My card is also recognized well on the Ryzen 5700X and B550 TUF motherboard.
I downgrade the processor to 13700K and the BIOS from 801 to 507. I reduced the card generation from Gen5 to 4 and 3. I tested the graphics card with an x1 riser in other PCH slots. I removed all peripherals, even the boot drive. It was useless. nothing. 3 BIOS beeps mean no image signal. Of course, I got display using the UHD 770 and confirmed that the device manager is not showing the 3080Ti.
Finally, setting the slot to x8/x8 cards miraculously returned to normal. my 3080Ti Passed stress tests but works on x8 Gen4 obviously.
What do you think? I guess I need to wait for an update or something like that.

[Silent_Scone]

Hi @De1222 
Did you attempt to update the GPU VBIOS?

[De1222]

@Silent_Scone 

Yes. It has the latest official vBIOS.

[JohnAb]

I'd be tempted to take an image of the OS and then try a fresh install (since you changed the CPU). If that doesn't help, then you can restore the OS and at least you'll be no worse off.

Take a backup of all files as well first, then if the reinstall does help, you'll be ready to put any files back on. 

[De1222]

Test with new 1002 BIOS, Still nothing.