yes but now i know exactly how much one card consume, the system apparently consume 70w when three card are mining
each card 147w mining at 22MH, same thing as 390, so those who were saying that amd was better, were wrong
possible lower with a reference 970 due to less components on board plus less fan, 140w estimate
I have 5x R9 390 XFX cards. 137 MHz with 870W from the wall, so that is 6.35J /MH, that is better than the 970.
not with reference card, it depend on the type of card, with a reference card that have 1 fan only and a smaller pcb you consume less
mine are g1 gaming you are running 390 that have probably two fan only and the pcb is smaller with less component, that's why you consume less
they are equal in the end, i can estimate a consumption of 140w with a reference 970 at 22MH so 5 x 140 +70w of the whole system(i have two fan added for cooling and my cpu is at 25% + 8giga ram)
so total is 700w, plus the 70w system, = 770w vs your 870w at 132MH vs 137MH, not better at all, only nano is better 970 and 390 are equal