Bitcoins and Litecoins: How to Build a Mining Rig

Some of you might think the time is past for building Bitcoin miners, and perhaps you're right. With Avalon talking about open sourcing their ASIC and Butterfly Labs shipping "any day now", we could see a flood of hashing power coming online in the next couple of months. Of course, I suspect the time it will take to actually get a wafer made, cut, and distributed -- and then tested, assembled, and more testing -- is more likely to be another six months, unless the original creator lines up everything so that you just have to order one. In that case, it would probably only take three or four months to get your ASIC from China.

As for Butterfly Labs, the jury is still out on whether they're a scam, an unintentional ponzi, or just highly incompetent with a horrible public relations/customer support staff. I actually emailed them to see if they'd be interested in sending me a unit for review; no response to the email so far, which means they're likely completely understaffed, or they're trying not to let any reputable hardware sites do any coverage. The ponzi aspect is pretty easy to get, though: you offer preorders for an "amazing ASIC" that can hash at 60GH/s while drawing 60W. Eventually, that comes out as 25GH/s at 150W, but demand is so high that instead of fulfilling long-standing orders for the 1500GH/s rigs, you start by shipping a few of your lowest performance solutions (5GH/s).

So far, apparently four units have shipped out, one to a blogger, and naturally that results in a ton of new interest. $274 for a 5GH/s Jalepeno? SIGN ME UP! Except, the current wait time is at least two months according to some sources, and more likely it's two or three times that long -- and that's assuming you ever get the hardware. If I could get a firm deadline, like four months, even now I would be willing to fork over the $1100 or so for four of their Jalepenos. That would net me 20GH/s and use a whopping 120W, which is 4X my current hash rate in about 1/30 the power use, or approximately two orders of magnitude better in efficiency! But they're still unproven, so until I have $1000 around that I can afford to lose, I'm going to hold off.

Which brings me back to building a mining rig. Bitcoin mining with GPUs is still quite profitable. For example, a Radeon HD 7950 can run at about 500MH/s without too much effort, and it will draw about 250W for the system. At the current exchange rate of $137 per BTC, that works out to around $110-$125 per month in BTC with a power cost of around $18 per month. So let's just call it earnings of $100 per month, for a $300 graphics card. Right now, difficulty is increasing about 10% every two weeks, so if pricing stays static you'd make $90 on month two, $80 month three, and after four months you've more than paid for the hardware and as long as the difficulty doesn't get above 60 million or so you should still at least break even -- and in the winter months, you can deduct some of the power cost from your heating bill! :-)

Litecoins are a different story, as ASICs aren't available and may never become available. With a 7950 and a bit of tuning, you can readily get 550kHash/s out of a single 7950. At the current price of roughly $3.80, that works out to $155 per month, or $140 in net income. In less than three months, you could more than pay for a Litecoin mining rig, even in today's pseudo-ASIC Bitcoin landscape. And yes, recently I even put together another Litecoin mining rig for just such a purpose.

Here's what I used and recommend, keeping in mind that you ideally want a motherboard that supports as many GPUs as possible. That rules out AMD's Trinity (FM2) platform, as those motherboards only have two x16 slots as best, and given the price and power considerations I decided Intel was a better choice. There are some big Extended ATX board that support four or more x16 slots, but they're expensive at around $300 minimum, so I figured a solid ATX board was best.

3 x Gigabyte HD 7950 GPUs @ $310 each (the triple fans mean less noise)
3 x PCIe x16 extenders @ $5 each (so you can better separate the GPUs for cooling)
1 x ASUS P8Z77-V Motherboard @ 165 (supports 3 x16 slots and has WiFi)
1 x Kingwin Lazer Platinum 1000W PSU @ $180 (room to spare on power)
1 x Intel Celeron G1620 CPU @ $52 (no need for a fancy CPU)
1 x Mushkin 2x8GB DDR3-1600 RAM @ $98 (you could get 2x4GB, but this gives you room to spare)
1 x ADATA 60GB SSD @ $70 (you could get a slightly cheaper HDD, but you don't need a lot of storage and the SSD is faster booting, cooler running, and generally more desirable)

Now, here's the big question: where to store all the components. I can tell you from experience that having everything in a case just makes for hotter quarters, so if you don't mind going ghetto you can grab a plastic crate and store stuff in there. Otherwise, I'd suggest getting a really inexpensive case that you can dismantle a bit, since you want to spread out the GPUs to provide better cooling opportunities -- the Gigabyte case should work. If you want a "real" case, though, I'd get a full ATX tower, and Silverstone has some good options like the TEK SSI-CEB for $100. What about the OS? Well, get yourself a copy of Windows if you must, or get comfortable with Linux for free. I may see about doing a Linux configuration guide for Litecoin in the near future, once I've gotten familiar with the process, so stay tuned.

Grand Total: $1510
Expected Returns: $500 per month

Note that rate of return could go up or down depending on price and difficulty. I expect it should pay for itself within four months at most. There's more good news as well. The GPUs come with a game code good for three free games, which you can sell on eBay for typically $50 or so each. Second, even if Bitcoin and Litecoin become unprofitable for GPU mining at some point, you still have a very nice system -- well, the CPU is weak so you might want to upgrade to a Core i5-3570K or a Core i7-3770K. You should be able to sell such a system for at least $750, even if you only have one GPU in it -- $1000 would be reasonable with two GPUs.

So mine for as long as it's profitable, make a few upgrades, sell the hardware, and you could easily earn $5000 extra this year. That's my plan at least! And I'd seriously consider saving all of your Bitcoins and/or Litecoins for a while -- I could see Bitcoin hitting $1000 in the next few years, so at 2.5BTC per month, decreasing 10% each month, you'd end up with around 25 BTC by that time. Or if you hold LTC, you could have 1200 LTC by the end of a couple years, possibly more. At that point, sell them for $25 each and pay off all of your debt!

If you find this guide useful, I gladly accept donations:
BTC: 1JSrAuxPUhD2rS6yYLiPPT6X8fvz7c7k1W
LTC: LXpEZcNJtikd263z7Ha3vrdYDcLU7hiKWv

Update: Need help? See my Toubeshooting Guide.