http://www.middlecoin.com/reports/18Y3Dhw1EdFTfzpVe4bKKhPgsQYuFWERLT.html
I have 13 rigs with a total of 42 cards active - all either 7950's or R9 280x's. Hottest card is 83, most in the mid to high 70's. CGRemote shows a total of 12 hardware errors and many of these rigs have been weeks without a reboot. The 7950's hash at about 630-670 while the R9 280's are between 690-735. While I haven't done the math on all 42 cards, the ones I glanced at are at least 85% WU vs. Hash Rate. Most of the 7950's are undervolted a bit and so are a few of the R9 280's.
Can anyone think of anything that I might be missing?
your numbers look almost exactly where I would guess.