I kind of played with wattool and polaris editor and I reached the next resulting.

6x + 470 Sapphire Nintro 8 gb
ASRock B85 ANNIVERSARY
Intel Pentium G3250T @ 2.8GHz

162-165 Mh / s on Claymore dual 8.1 @ 669 watts on the wall  

per card 27+

cca 101-103w per card, Others consume the rest of the system

gpu core 1050 / 820mV
mem samsung 2050 (strap 1625) 900mV

For me, the main energy saving and efficiency.