Was happening to my wife’s computer on 6800xt during beta and release. Tried a different OS drive and it’s stable as long as I also remember to spin the fans to 90% or higher.
My 3090 and OS have been fine during the beta and the first week. Come Saturday and it’s a mess. The shut down gets triggered by HDR and on Character Select screen. Windowed mode and HDR off helps get passed it by eventually crashes after an hour or so. My GPU and VRAM have waterblocks. Temps aren’t the issue