trouble shooting System won't Post with Graphics Card in x16 Slot

[UIJess]

Hello there, I'm looking for some help solving this problem for a computer I am building for a friend.
I built this computer outside the case and found that all the parts seemed to work, but when I put it together inside the case it wouldn't post(fans spin but no display out) about 1/4th the time. Through a long process of trouble shooting and rebuilding I found that the booting issues only happened when the Radeon Pro WX 9100 was put into the Asus Prime Z690-p WIFI D4's gen 5 PCIE x16 slot. I tried a few things to see if it would help get it to work. I reseated it a few times, made sure bios and drivers were up to date, and tried set the speeds to gen 3 in bios to see if it would help. It seemed more consistent, but it would still occasionally not post. I changed the slot it was in to one of the other gen4/gen3 slots and it seems to be working fine now, but I would like to get it work in the gen 5 slot, know why this wasn't working and if there would be a real world performance difference running this graphics card in the other slot. 

Specs:
i7-12700k
Asus Prime Z690-p WIFI D4
Radeon Pro WX 9100
4x16 G-Skill Ripjaws DDR4 3200
WD black 1TB nvme ssd
Corsair AX860
Corsair 4000D airflow

The power supply and the graphics card are from their older system. Tested this with another power supply and had the same results.
Thank you for your time.

[191x7]

That's a PCI-E 3.0 card sdimilar to the Vega 64. Strange that it doesn't work in a PCI-E 5.0 slot, but there's no harm running it in a PCI-E 4.0 or 3.0 slot since a slot faster than 3.0 doesn't mean a thing for it.