I'm mining at around 125 watts / card ( really high, how you guys can mine at 80-85 watts ? ) , power consumption of 82%, core memory + 50. Using CCminer 2.0, windows 10.
There is your answer in bold.
My 5 cards draw 350W from the wall, which comes down to about 70W, minus the CPU and other parts of the computer, so the real wall power draw is less than 70W per card.
I run +600 memory and 55% power consumption. Downclock your GPU as much as possible.
But I have quit mining Ethereum. It's good however for people with high power cost (me, I just don't care, I mine coins which are cheap now and have potential to go x10 in the future, giving me x10 proft).