I just installed the Hybrid kit for my 3090 FTW3 Ultra. I'm constantly getting black screens, whether in the BIOS, or if I boot into Windows for more than 10 seconds. It looks like the display just shuts off. My PSU is the Supernova 1000w P2 and I'm using the MSI z590 Pro Wifi on a 10850K. Every once in a while the fans kick into a turbo mode which makes it very loud. I did use the onboard graphics which worked fine, but I didn't see the GPU in device manager. When I am able to boot into Windows, I can check device manager or in Precision X1 and I see the card recognized as NVIDIA RTX 3090.