The 75-80MH is for each 1080ti mining Lyra2REv2, I have 5x of them currently (one is in my gaming rig, one in my home server, and 3x in a mining rig that consist of a dog crate with a box fan ziptied). About $800 a month at the current rate. I hash Lyra2REv2, Equihash, X11Ghost, Lbry, and Pascal, whatever is the most $ at that time, $5-8/day per card.
What's the power cost on all those rigs? $50?
Either way, you are paying for a 1080ti per month like that. Did you get all the cards just for mining? Or did you already have them for some other reason?