I’m on my 8th rig and starting to have the same problem as soon as I start installing 3080s. My first 7 rigs were all 3070 and never had any issues in the past. I’m currently testing this setup but still having the same issue. The problem was semi-solved when I tried to reduce the number of GPU. I think the problem either mixing 3080 and 3090 or my PSU cannot give enough juice to power 3080 and 3090. I got the same issue when I added a 3060 into my previous rig with 3070 only. Resetting my BIOS helped me with another rig.
I just bought a Corsair HX1000 Platinum 1000w to give it a try. I will also reset my BIOS. I will keep you guys posted!