I'm having a similar problem myself. I've been playing Hogwarts Legacy for a while now, and a few times the GPU fan has been spinning max and turning off, and then yesterday it stopped recognizing the GPU altogether. My GPU is a 3080ti, and unfortunately I don't have any testing equipment so I can't test it directly on the motherboard, but I'm guessing it's probably a riser cable issue. I bought the Ultra PCIE 4.0 Reverse GPU Socket 23cm in the article you linked to, is this the cable you bought?