Even with S7, he would lose money at 21 cent/kWh. He could have made some money by mining Ethereum.
But add up cost of 6 GPU rig with nice GPU's.... it's pricey. Do you believe enough in a in a alt this much? Could be a 2 grand guess depending on cards. I personally sold most of my GPU's long ago and worked out well. I am hesitant to spend big and build nice rigs on a alt currently. Compare to S7 coupon price, its a much higher investment.
And really you should not be mining anything at 21 cents. This thread is all about that your killing your ROI by mining with such high electricity price.
a six gpu right cost you around 2500-3000 max, this is 5 antminer s7 right?
but you need to compare also the consumption
5 antminer consume 6kw, against 1kw for the six gpu miner, 5 antimer s7 earn you around 0.07, a sig gpu miner earn you the same basically(2 ethereum a day= 0.058)
For the time being, it is very profitable for GPU mining of the Etheruem. If it becomes not profitable, you can sell the cards.
This is true but I just have trouble going back to GPU, and it could just be a personal thing. I can remember selling off my rigs before when I stopped GPU mining a ways back..... that is a good amount of ebay sales. So you counting on a lot of good buyers and not crap ones, not to mention dealing with low ball offers, shipping, etc.
If Etheruem has problems and you do need to sell, you also compete against all the others getting out of mining it. That is part I really don't like. A LOT left gpu mining around the same time with asics and you were selling cards cheaper due to volume of sellers. So .... again not fun.
Also GPU time I had to babysit a lot more then I do with my asics. I have had some asics hit a month + without me touching them. I had a lot more time then this monitoring my GPU rigs.
I'm not saying I won't try it if I see a long term mining, that I can believe in. But I'm not to that point yet personally.