Good cards. But they draw 200-250w. The x11 kernal is not optimal. You should mine something else.
4 750ti's draw 260 watts.
4 R9 Nano's draw 400 watt while doing 11Mhz..

And 4 750ti do 12.8 mh/s at about 260 watts.

And a 980ti does 13.5 mh/s at 310 watts at the wall..so about 240 watts.
EDIT Make that 360 watts not 260 watts.