If that PSU was having issues, it's a lemon. I think Phil was running on 120V back then too. 240V is easier on the PSUs, I hope you'll be using 240V with 6 S7s?
EVGA says you can pull 1300W DC from them, IE ~1450W at the wall for 10 years. That's good enough for me! Worse case they replace the PSU for free.
That's good to know as i was getting nervous after reading what Phil had to say. Looking at graphs, efficiency is decreasing at least 5% at or above 90% load.
Yes, I was running at 110/120V, but I send them all out to hosting with sidehack-posted review in Hosting service thread.
I like his arrangements and service.
Aside from the decreasing efficiency which for ATX supplies actually largely is from the fans running near/at full speed and taking more power to do it, with ANYTHING dealing with power be it plug/circuit ratings and including PSU ratings always follow the 80% rule. For the feeders it keeps plugs/cords/wiring behind walls at safe temps when under a constant near-max load - which miners present - for the PSU's you need that margin to handle the random (hopefully) short-term events all powerlines have.
For example of pushing ratings just talk to Bitmain and their experience with early s2 PSU's.... But as long as you have spares to cover ya while EVGA ships a replacement then your call. Und ja, as has been often said, any PSU is much happier on a 208-240v line because of the lower currents on the AC-line side of the power conversion.