For those curious how zcash compares
3x 1070's 1220 sols/s 410w (85%TDP +50 core +550 memory)
2x 980Ti's 860 sol/s 530w (100%TDP +75 core +350 memory)
2x 1080Ti's 1240 sols/s 415w (80% TDP +25 core +300 memory)
The 1070's can about equal the 1080ti's when the ram is pushed to 650, but they cannot hold that stable over night, the 980Ti's card for card equal the 1070, but require an extra 100+ watts to do so.
EDIT:
Oh and here is balls out on the 1080Ti's just in case you are curious how little core clock matters (to a point)
and here is my 1080Ti's ignore the ugly cabling trying to decide what the hell I am going to do with that.