My 2080Ti FE has been causing complete sudden system halts under load (First instance running FFIX bench, after testing BF1 @144Hz ULTRA settings, then again just in bf1 on an empty server). I'm not sure whether it's a faulty GPU overheating or my Corsiar HX850 (mk 2 IIRC) failing to supply the juice. It's been fine with my overclocked 6900k, watercooling and a pair of 1070s, but maybe the 2080Ti has pushed it over the edge (Although it is supposed to be a single 12V rail with 70A available). I've got my 1070s back in at the moment and it's running flawlessly. On paper as the 1070s are OC models they draw ~170W each while the 2080Ti is supposed to be less than 300W, but I guess if the boost clocks are much higher than the stated 1650MHz then the power rating is probably bogus. I estimate my CPU is drawing ~250W, not sure about the 2 d5 pumps in the watercooling.
Anyway a 1000W Superflower leadex 2 80+GOLD is arriving this morning, with the extra 12A on the 12v rail that should determine whether it's the GPU or not (It was getting very toasty though). Fingers crossed here as I expect an RMA to Nvidia to be a long and painful process if it is the GPU.