Unless that was 880W output, which at 86% is 1020W at the wall. 880W output at 90% is about 980W, close enough to the same difference for these calculations, but 880W continuous from a 1000W consumer-grade supply definitely greatly increases your odds of failure.
I wonder how hard it'd be to jack a DPS-800 into it instead? Running off 220V that'd handle the load pretty easily.
found a review.
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=270
I think this is okay to run 2 s-1's at 720 watts 24/7/365
but 2 modded dells are under 160-170 and this is over 200. and the 2 dells will do 3 s-1's over clocked to 200gh at freq 393 or 400
my guess is people will have problems with this enermax if it is what is supplied with the s-2