The first item I picked out was the motherboard. I opted for the Gigabyte G1.Sniper Z5S. The board has three PCIe x16 slots and four PCIe x1 slots, so theoretically I could run seven GPUs. At $149.99, it wasn't the cheapest option. The ASRock Fatality Z87 Killer also has three x16 slots and four x1 slots and that board is only $124.99. Yes, there are even cheaper boards, but they tend to have PCI slots that I'm not going to need or use.
Since I'm strictly GPU mining here, the CPU can be minimal, though I do want it to be efficient too. Any power used up by other components isn't going to the graphics cards. A Celeron G1830 will do nicely and they're only $59.99.
Memory doesn't have to be top of the line, but since we're Corsair, we can get away with a little overkill using our own products and we have a lot of good stuff lying around the office, so I opted for two, 4GB sticks of Corsair Vengeance PC3-12800 SDRAM, which would normally run you about $89.99. But to be honest, you could easily get away with a couple sticks of 2GB and that will run you about $30.
Yes... they're green.
For the hard drive, I might as well use a Corsair SSD we have laying around too. I don't need anything big, so I'm going to go with a Force 60GB which is normally a $74.99 drive, but you could just as well use a standard platter drive for just under $50. If your system is stable and can keep running 24/7, you won't be bothered with slow load times.
Next, and the most important part, the graphics cards. They're important because their GPU's are going to be doing all of the hash cracking. Yes... ASICs are WAY more efficient at mining, but they're even more expensive than a high end graphics cards, and it turns out that a lot of the folks supplying ASICs are simply scammers.
We do realize that Radeon HD 7990's are the best cards for mining if you're going to GPU mine. And why wouldn't it be? You're essentially putting two 7970 GPUs on one card. But they're very expensive (around $650 a pop), and that's IF you can actually find them in stock somewhere. It looks like we're just going to have to go with HD 7970's instead, specifically the XFX "Double D" R7970 GHz edition which were $429 each. We picked up five of these.
Since we're experimenting here, we also decided to get a couple of the PowerColor R9 290X. The performance and power consumption are typically similar, but we want to see what each card can do when mining when all other components are the same. This card might be harder to justify an ROI on... especially if it doesn't do much better at mining than the R7970. This card cost us a hefty $699, so it would have to mine at a hashrate that's 1.6 x better than the R7970 to see an equivalent ROI. Because of the high price, we only picked up two of them.
Now we need something to power all of this. Here in the U.S., our homes use 115V. The disadvantage of this over other countries that use 230V is that it requires more current to power something like a computer. We're going to use the brand new Corsair AX1500i PSU.
Using this PSU will give us 1500W of power and we're not going to need to run a special 20A capable circuit or 230V to run it because the AX1500i is so efficient (80 Plus Titanium efficiency) that it will still draw less than 15A peak (the limit of your typical, U.S. household power outlet). If the PSU were Gold, or even Platinum, we run the risk of tripping a breaker.
There's also the consideration of ROI for the power we're going to use to run this machine. A more efficient power supply is going to cost us less money to run. And with the Corsair Link software, we'll be able to monitor and log our power usage and calculate how much money it's costing us to run our crypto-currency mining rig. So while the AX1500i will have a retail price of $449.99, we definitely see both ROI and benefit from it's efficiency and ability to monitor our power consumption... never mind the fact that we'll need this much power for all of these graphics cards!
So these are our core components. Whether we're going to end up using all of these graphics cards remains to be seen. And we still need a chassis to put them all in. Of course, we'd like to use a Corsair case, but we're not going to be able to fit this many double slot graphics cards in one case. Shoot, we're going to need to overcome putting this many graphics cards on one motherboard. We think we've got it all sorted, but you'll have to wait until our next blog to find out what's up! And if you have any suggestions or comments, please don't hesitate to post them!