Maybe it's just an average card idk? I just rewired the whole build to make sure that every sata riser has its own individual sata cable and that each card is powered by the same psu powering the riser. No difference. That card still runs at 670-690 sols and I have to run it at 85% power. The other EVGA card must be run at a max of 90% and gets ~700 sols, and the good EVGA card runs at ~740-750 sols at 100% power. The Zotac cards aren't bad... I have them at 85% (although they can run at 100% no drama) and they get 750-760 sols (they get ~780 sols at 100% power but that's an extra 50W per card). I'm pretty happy with the 1070's, getting ~480 sols per card.
EDIT:
Been monitoring voltages for each EVGA card. For all 3 EVGA cards set to 85% power with the same overclock. They are all drawing around 210W at this power setting.
Card 1: 0.900V - 720 sols
Card 2: 0.875V - 690 sols
Card 3: 0.825V - 650 sols
Card 3 is the problem card. After starting the miner program it will start out at around 0.875V then slowly decrease to ~0.825V then the miner will crash
My power supplies have multi 12V rail and single 12V rail, not sure if 1 is better than the other. Tried both and neither seems to make any difference.