these are nvidia 1080ti's with a bios mod.
so you can put 200 watts in and get 700 sols for equihash.
or you can put in 200 watts and get 48mh
so you would need to pay under 350 for you rx 570's
these cards will unlock to 11gb not the 5fb they are locked to.
and you can buy these in bulk.
You can thank the miners that purchased a ton of 1080tis and the run them at 110% tdp not caring if the card dies as it has a 3 year warranty.
So Nvidia came up with these which are geared to miners.
Nvidia has restricted sales of normal 1080ti's to prevent miners from buying them and burning them up.
here is an evga deal that appeals to a gamer but not a miner
it is 1169 usd too much for a miner that does not need the mobo
but decent for a gamer that will mine a little while he sleeps.