GPUs: (NVIDIA) 3 EVGA GTX 1070 SC , 1 EVGA GTX 1070 FTW, 2 EVGA GX 1070Ti FTW
Moboard: ASUS Maximus Hero VIII
Hashrates: keccak ~5GH/s, neoscrypt ~7.2MH/s, Blake256 ~34GH/s, ethash ~180GH/s
I need to dress some cables and move the fans higher. Heat rises... duh... but 6 cards, stable and productive... I've had all 6 up for about a week now (after running 3 for a while waiting to buy 3 more GPUs and then 5 for a while waiting for the right power adapter. I have done some tuning to keep it stable and some testing to see what it will actually produce. Let me be 100% clear here, I DO NOT MINE BITCOIN. But I will use BTC values and USD values below because I am mining several coins and don't want to list current USD approximates for each.
If I go for straight up "most profit right now" mining style it will make about 0.005 BTC per day. If difficulty never changed (which it does) and everything were stable (which it isn't) this thing would earn about 1.825 BTC / ~$22,000 annually and the electricity is about 95% covered by my rooftop solar production. In reality mining doesn't work like that. Unless you are mining ETH which is fairly stable, mining projections based on a week of testing are worthless.
In December of 2017 I mined about 1,800 SMART. I mined several other coins as well, but let's just look at SMART for now. A good deal of my SMARTs were mined when SMART was worth under $0.10. Now, after a good bit of price easing after a blockchain fork and rollback leading to a prolonged period of limited ability to deposit to or withdraw from exchanges, which in my opinion caused an artificially high price for SMART. If I would have sold my SMART when it was at it's highest point, it would have paid almost twice as much as my cost for the entire rig. If I was only mining for short-term gain, I would have.
When I first got into this, I did a lot of research (mostly academic being that I only had one AMD RX 570) and my projections based on the prevailing wisdom at the time was that it would take about 3 months to pay the cost of the hardware back. As it turns out, thanks to some luck and some good research and good decisions on my part, about 60% of my rig's hash power (I did mention I've been mining other coins, not just SMART) could have paid back my initial investment and returned 100% within about a month. Instead, I've pooled with a friend and we invested the SMART we mined and some that we bought towards a masternode. Time will tell if our research and decision were good. But I'm hopeful.
As for SMART, $0.70 feels more right than $3.00--at least for now. Once InstaPay is done, then we'll see. Right now $0.70 SMART might even be a little high. In any case, my point being miners are converting computing power / electricity into something with a fluctuating value. At any point any number of other actors could decide to mine the same coin you are mining and thus lessen your share. The only more or less constant part of the equation is the cost of electricity. So if you're doing this for income... buckle up and get a helmet. You're in for a wild ride.