It's a shame you're thinking of quitting. With two 1070s running for long enough, I'm planning on upgrading the rest of my rig using the bitcoin I've mined with them someday. I may have missed a few things, but, from my own experience, I have some questions.
1. What motherboard is it?
2. Are you plugging the cards directly into the board, or are you using risers?
Most boards aren't designed for this, but some are, some with such radical configurations like multiple 24-pin connectors and extra molex or even PCI-E connectors everywhere to help power the PCI-E slots. Which brings me to why I asked about risers. Any board can do big mining with the proper risers. Some risers not only allow you to expand a puny PCI-E 1x slot into a full x16 slot (it won't be true x16 electrically, but at least it will physically fit, and the cable length allows you to put the cards in weird non standard configurations like you see in these open air mining racks), but some are also powered, by molex or SATA power connectors or something. This is important because the PCI-E slots, at least in cheap boards, draw power from the few +12v leads in the 24 pin connector, and when you draw too much,
bad things happen, check near the bottom of the page. Boards specifically designed for mining take this into consideration, and that's why there's additional 24 pin, pci-e or molex connectors everywhere. Or you can use the aforementioned powered risers in any board which will be powered by a separate molex or SATA connector or something, which means it won't be drawing a fuckton of power from somewhere it shouldn't be.
I'm still using that same board and power supply. The 24 pin connectors are still burned up, but I did ghetto repair the burnt up wires on my power supply. Since then I used afterburner to lower my power target to 80%, which hasn't hurt my hashrate (in fact it's a little better than stock because I also overclocked the memory), but it has lowered the total power draw by around 60w. The cards went from 150w to 120w. Just as an example, if you had 5 1070s instead of your cards (using the 1070s as a reference point because I know them well), if you lowered the power target to 80% like I did, you'd save 30w per card, a total savings of 150w. That's like having one less card running, but it wouldn't affect your hashrate much. That's good news for your power bill, the heat output of the rig, and the strain of running so much power through one rig. My shit hasn't burned up since I made that ghetto repair back in August of last year.
As for the payout, yeah, it's low right now. When I got into it I expected to be making $10/day off my two 1070s, but alas, together they're now making $2.50/day as I type this message, and the true value of that is ever sinking as BTC loses value. However, I've been in it long enough to know it rises and falls, and the ~.038BTC I have now may be worth about $280 today, but if we ever see a day where BTC hits $20k like it was in December, those same BTC are worth $760! This is not a second job, or a steady investment in a safe place such as a high yield savings account, or CDs. This was, for me, a step into a risky side-hustle to make a little extra money. Fortunately, it's saved my ass a few times already, and now I'm slowly building it up for a fun purchase when the time is right.
You spent a lot on this rig, and at present, it will take a long time to recoup your investment. But as those of us who've been in it a while know, this thing goes up and down, some days are better than others. For those with stored BTC, if BTC explodes we all have a little bit more. If Etherum explodes, everyone running DaggerHashimoto will be seeing higher payouts than we are now. It's a risky world full of unknowns and what ifs, but if you stay in it long enough, there's a fair chance you can come out on top.
