Yep, it is 30 GPUs. I don't want to waste my time selling it one by one. I already have such amount of GPUs. I just want to lower my cost of farm, because previous ones where bought in 2017 December 2018 January when high prices kicked in... Speaking about el. consumption I will squeeze easily 6GPU rig to 700 Watts with 180MH/s. So 3500W in total, i don't know how leowonderfulcould make them run with only 3000W.
I haven't mined with 570s in a while as I've sold off most of my rigs and I used numbers from a post I saw on another forum I saw a year ago, my bad considering I was just guesstimating. Still, it's going to take a bit of time to break even like fanatic mentioned if you plan on just mining and not immediately selling off the parts, and if you do choose to go through with this, the resale value offsets the risk somewhat. If things don't turn out well for you and you've mined for a few months, you'll have broken even and then some, and the 570s likely won't drop too much further in pricing soon.