Topic: Running an S7 on two PSUs (120V Not 240V!) (Read 1228 times)

Correct, I consider this thread closed. You guys all helped me with my questions and I have some solid info now so thanks to every one who helped. Good luck to everyone and your mining. Cheers.

Not really. That guy was a thief. I'm just some guy with a contrary nature and enmity toward greed. But none of that has much to do with how to safely run a 1400W miner off a single 120V circuit.

You're like the Robin Hood of bitcoin.

good

I don't really run many miners of my own. Can't really afford to buy in, all my resources are tied up in paying the bills and building stuff for everyone else. My hosting exists to be affordable for little guys who aren't getting any breaks like the big farmers do. From the beginning I've not liked big farms strangling out the little guys and I won't be offended to see some go offline.

Sidehack don't you have somewhat of a decent mining operation going? I thought I saw you offering hosting options for guys in the Avalon group buy? Aren't you a little worried for your farm and profits? I'm not familiar at all with the size of your operation but I'm just surprised about your last comment.

I'd assume the diff would drop briefly as a lot of currently viable gear gets shut down. Some of it may come back online if the diff drops far enough, and if that gear is resold to someone who can run it viably, which will probably cause some interesting oscillations in the weeks or months immediately following the halving. The reduced flow of new coins won't affect the overall supply that much, so scarcity won't cause much of a price increase. If the price increases it'll be because people want it to increase to keep miners viable, or ideally because of increased demand from increased utility of the currency itself.

But yeah, a lot of farms will probably go under. I'm not offended by that.

The halving event introduces a great deal of uncertainty into  mining profit and loss calculations. The only thing we know for certain is that the reward will be cut in half, and as a result there will be 1800 BTC produced in a day (roughly). What we don't know is:

1) What will the BTC price be before and after the halving?

2) How will the humans respond in terms of their willingness to pay for X Th/s of mining hardware?

3) Presumably some mining operations will have to give up, since they may not be able to cover their fixed costs. Some think that will longer term reduce amount of hash rate. I think it will reduce the price of used mining gear.

The difficulty will be unchanged, and increasing your hash rate to try and compensate won't have any effect past the next difficulty adjustment. Your electric bill won't change. You'll leave work on Friday getting Y BTC/day, and on Monday you'll be getting half that.

Some folks have tried to look at the previous halving (i.e. from 50 BTC/block down to the present 25 BTC/block). That was a while ago, and there wasn't nearly the network capacity and investment in hardware and infrastructure.

My thinking is that the current ASIC vendors wish to make all they can in terms of hardware in the fear that the price that folks will pay for hardware will decline leading up to, and following the halving.

Lot's of speculation on what will happen then.

You guys are both right and can't believe I didn't add that in. Taking that into account it would mean the best course of action would be to sell off after the halving making the total profit for 7-8 months (assuming halving in July) only around $52 per unit.

I understand that mining farms have very low electricity costs but even after the halving occurs how can they stand to make money without selling off their mining inventory for whatever they can get? Also this would greatly flood the market with S7s dropping the prices they could get even further. I know there is some development going on with smaller more efficient ASIC chips, but with the difficulty and halving happening the miners would have to be EXTREMELY efficient like double what the S7s were to be profitable again. What am I missing that's not keeping these places from going under in the next few months?

The comment on the "Block Reward being reduced to 12.5 BTC" (aka the halving) is right on the money. That event is not accounted for in most of the on-line BTC "profit calculators".

One minor quibble. The expected date of the "halving" is more like July than April. Some quick Google research will get you a moderately accurate date.

The halving is coming April which you didn't include it seems

Looking at my calculations if I could mine from now till end of December (assuming increase of 10% difficulty and 1%BTC price increase) I could end up with $160 - $180 of profit assuming i sold the miners at 50% of what i payed for them at the end of the year.

Month Diff.   BTC Mined   BTC Value   Profit
Jan   112   0.63313112    $275.41     $2.28        ~~~~~~~~~~~~~~~~
Feb   123   0.569818    $253.57     $(19.56)                    l
March136   0.512836    $230.78     $(42.36)                    l
April   149   0.461553    $210.01     $(63.13)                    l
May   164   0.415397    $191.08     $(82.05)        Miner buyback period
June   180   0.373858    $173.84     $(99.29)                    l
July   198   0.336472    $158.14     $(114.99)                  l
Aug   218   0.302825    $143.84     $(129.29)                  l
Sept   240   0.272542    $130.82     $45.81   ~~~~~~~~~~~~~~~~~~~
Oct   264   0.245288    $118.96     $33.96
Nov   290   0.220759    $108.17     $23.16
Dec   320   0.198683    $98.35     $13.34
            
      4.54          $2,092.98    
                 Power     ($1020.10)
              Sell miner   ($600.00)

 Yearly Profit per unit     $167.88

Factor in resell value with the S7 as well. You might not get your ROI mining bitcoin but mining for a few months than reselling might exceed it pretty easily. The halving should be interesting for miners.

I will pull off the breaker box shroud another night and check the wire to see what gauge just to be double sure. And yes I was talking about a GFCI built in.

Have to do some more calculations to see if mining an S7 can even cover my costs through the next several months with difficulty. If I can't make anything with an S7 I think I'll need to give up on home mining for the time being.

If it's proper-sized wire (which it better be!), a 20A circuit should have no trouble at all with an S7. Garage door opener probably doesn't pull much power, but it might be worth testing it with your heater plugged in and running. The worst-case instantaneous draw will probably be if the door jams (or someone kicks the laser) and reverses direction suddenly.

When you say trip/reset switches, do you mean GFCI outlets? That doesn't really protect against a current overload, just cuts the power if it detects current on the earth ground (which usually indicates something in your PSU is going very wrong).

Alright guys finally got home and checked out my box. Looks like a have an entire 20A breaker just for the plugs in the garage. All other major appliances are on different circuits. The only thing that shares power with receptacles in the garage is the garage door opening motor. The plugs also have the trip/reset switches built in which makes me feel a little better.
I plugged in a 1500W floor heater and ran some power tools last night and never had an issue. I know that's not a great way to measure if the circuit is up to the task of running an S7 all day but I'm willing to give it a go.

I'd be leery of running it if I saw a 5V drop in the wiring. That's a lot of power loss. But then I've never liked 15A circuits; the smallest I've ever liked to install was 20A with 12AWG wiring. For a few months in early 2014 I had five S1 running off three load-balanced 750W on a single 20A circuit. That wire got a bit warm, but it wasn't 20 feet from the panel and, being a ceiling run in the basement, was open-air exposure from end to end.

A B8 S7 at stock speed will consume a bit over 1440w at the wall with anything but the better end of a gold efficiency. With two EVGA G2 at 50% load i got 1440W exactly after i brought down the fan a bit, but my 120v circuit drop to 115v when all the miners are mining so, something to keep in mind.

What do you mean by this?

Yeah this sounds like the best option. I took a quick look at my breaker box last night and did see a few rooms with double 15A Breakers, I imagine the garage/kitchen would be some of those. I'll pick up the outlet checker at Lowe's tonight on my way home.