Is Mining Worth My Effort? How Much Can I Expect To Make?
A system like the one I built is capable of around 2,600 Kh/s. Based on today's difficulty rating of 3.13K, you can expect to generate about 0.84 Litecoins per day, 25.06 coins per month or 305.16 per year according to the Litecoin Mining Calculator before pool fees (if applicable). Of course, difficulty is adjusted every 3.5 days and can either go up or down to ensure that blocks are found every 2.5 minutes.
As I write this, Litecoins are trading at $20.33 so you'd make about $17 per day or around $510 per month with this setup if everything stayed as it is today (it won't). But that's only half of the equation. You have to account for what your miner cost to build and if you're following my build, that would be around $3,000 before shipping assuming you don't already have some of the components around.
At today's rates, it would take about six months to break even if everything stayed the same (again, it won't) and that's not factoring in how much it will cost to operate your miner in terms of electricity. My numbers are a bit skewed here as I also have two other cards (a 280x and a 270) operating in a secondary machine, but my latest electric bill shot up exactly $100 with the miners running 24/7.
The systems are using a lot more power than I otherwise would but I'm also running an air conditioner a lot. At one point, it was around 10F outside and I still had to use the AC to keep an ambient room temperature of around 72F. The electric bill will only climb even higher during the summer months.
On top of the heat, a miner of this caliber also generates a lot of noise. The 290x's reference cooler is the main culprit as its single fan needs to spin at a very high RPM to keep temperatures under control. Many have bashed AMD's reference cooler for being inadequate and noisy. The dual- and triple-fan coolers used on most 280x cards are more efficient and much quieter but there is a catch.
Such coolers don't do a good job of expelling the heat out of the case, which makes them bad for coin mining in a conventional PC case. The reference cooler, however, blasts hot air out of the back of the chassis. If I had to do it all over again, I'd try to get a third card with the reference cooler instead of the dual-fan cooler on the 280x as it was one of the main reasons I needed so much extra case cooling.
A spare room on the other side of the house is probably where you'd want to keep a high-end miner and even then, you might still be able to hear it. It would be possible to eliminate a lot of the fan noise by water cooling the cards but that introduces more cost (and risk). Another option would be to put the system in a garage during the cold months although I'm not sure how condensation would factor in.
Another consideration: if you plan to run your miner(s) in a room with a lot of other heavy-draw electronics, total power draw could be problematic. During configuration, I had the miner in my living room and it tripped the circuit breaker. I had to move the system to a different outlet in another room.
I know one person who has miners running in his attic. With less insulation than the rest of the house, this eliminates having to run the air conditioner more than usual and also puts the systems out of earshot but he will need a different strategy once it starts to warm up outside.
Another option is to move the miners off-site completely, say, to a data center. You'd need to check around to see what is available locally but it could be cheaper to operate overall, not to mention you wouldn't have to deal with the noise.
There are a ton of questions that you'll want to ask yourself before mining Litecoins. If you're looking to make a quick buck, mining (based on today's rates) probably isn't the best use of your money. If you view Litecoins strictly as a long-term investment, your cash might be better spent buying coins directly and saving them for a couple years, though it's anyone's guess where virtual currencies will be by then.
However, if you're intrigued by the idea and love playing with hardware, it can be rather enjoyable. All I know at this point is that I've had fun with it and am ready to see what the future holds, good or bad.