I've run Batch 1's, Batch 6's@ 4.5TH with zero issues.
I've also run a few sets of 2x S5's overclocked to 1.25TH each for months with zero issues per EVGA 1300 G2.
Yeah but thats 1220~1300W at the wall. With B8 and B9 S7's, what Bitmain is selling right now, you're looking at 1415~1480W at the wall depending on PSU efficiency. So still fine, but very limit.
The efficiency of those is about 0.3J/GH/s with gold efficiency, versus 0.25J/GH/s of the early S7 batches.
Ahh, forgot that the newer batches' efficiency is crap.