I fresh install windows upon getting a new component most of the time or every other 6 months - no bloatware, just windows update
Tried DDU in/out safe mode
Different drivers, driver/package only
No risers, 2 power cables, tried both oc and silent bios switch
Tried GPU in another Intel machine which was on the side, made no difference (no sag)
Tried optimal settings in bios, tried auto and other pcie options
rx 3070 and 3060 tested with zero issues
I have pretty much tried every possible trick in the book and failed
Yeah I would put money on this just being a faulty card, even if OC test the card and its ok, you can't even sell it on given you have tested in multiple configs. I did wonder if OC have there test benches setup so the card maybe is vertical in position so maybe a fault on the PCI or a crack in the solder isn't picked up. Either way I hope you get it replaced and when you do whatever you pick do consider that its not AMD at fault here although I know how that can affect your bias.
Might be worth letting OC see this thread so that they can see others replies etc. Should get it resolved.