Bitcoin Forum

I'm considering building a 2 or 3 card mining box which I'd like to run 2, or 3 5870 or 5970's on. I realize getting three 5970's to work in one box might be hard to do on used hardware, so, whatever it takes to stay as cheap as possible.

Anyone have any advice on what motherboard and case I might go for?

I'm not going to have the cash to buy the GPU's immediately, but I'd like to begin thinking about getting the barebones of at least 1 standalone miner running soon.

Any advice is appreciated.

If you don't already have the system you can probably just forget about it. Difficulty is only going to rise, and most of those who buys big systems to mine do it to sell them, so the value of BTC will most likely stay low. The people joining BTC to mine now aren't libertarians who believe in the BTC and want to keep it to use it as a currency, they just see it as easy money. I believe this will push the price down, because the libertarians will run out of money to buy all the new BTC on the market.

I agree with you that difficulty is going to make mining infeasible for the individual.  However I disagree about price.  Price will continue to go up especially now that demand is high and creating new bitcoins is exceptionally difficult.   What new BTCs are generated will come at great cost in terms of hardware and power.   The will demand higher prices.    It's hard to believe you could buy 10000 BTC for less than $50 less than a year ago.  At that time a mining rig was a GREAT idea.  Now it seems dubious unless your willing to hold on to your generated BTC for a while.  So you spend $1000 on a rig and generate 500 BTC with it starting today.   In a year or so the 500 BTC may be worth enough to have made it worthwill.   

You can't put more than 2 double-slot GPUs in a box and still keep them cool without some kind of custom (expensive) cooling system.  So stick with 2 5870s or 2 5970s (good luck finding a 5970).  As far as motherboards, I've used the following, and they are both good:

ASUS M4A79XTD EVO
MSI 870-G45

You want a mobo that will provide one empty slot between the GPUs to allow sufficient airflow.  The MSI 870-G45 has the second GPU in the last two slots, and this can restrict airflow if you are using a tower case with a top-mount PSU or a rackmount case as the GPU fan intake will be next to the case wall.

As far as cases go, I'm a big Cooler Master fan.  I highly recommend a bottom-mount PSU design where the PSU can draw in cool air from underneath the case (mount the PSU fan-side down).  The PSU is the most likely fail point in a mining system because the GPUs will simply throttle if they get too hot.  You also want to be able to mount a high-flow fan in the front of the case blowing air directly on the GPUs.  The Scythe Ultra Kaze is excellent for this purpose, but it is loud.  It's also 38 mm thick and won't work with all cases.  I try to avoid side-mount fans because it's an extra step to remove the cover, and you have a wire dangling which might get caught up in a fan.  Make sure that the case you choose has sufficient clearance for the graphics adapter and that the drive bays do not block the airflow from the front fan.  With all this in mind, the Cooler Master CM-690 II is an excellent case for a mining rig, as is the HAF series (the cheapest HAF-912 works just fine).

You should put your rig on a table or shelf to avoid sucking in the dust which invariably settles on the floor.

Will an 850w Corsair power 2 5970's sufficiently?

Yes.  I'm using a TX850 with 2 5970's and a Sempron 140.

I'm thinking of this box serving as a media backup/storage server for myself as well.

Will the cheaper coolermaster case serve with enough room for at least 2 hd's [with 2 5970's] with adequate airflow?

Edit: Also, what about running headless? I've heard there's problems surrounding this but I really don't have a spare monitor to use. Am I going to have to get one, or what?

i would recommend using a monitor to set the system up, and install a vnc app or rdp app onto the computer so that if you do need to use the computer for something you can just log into it. if you are using windows on this computer i would recommend using windows live mesh because this will let you rdp into the box from any ware, and it will sync any files to the computer, so if you want to use the computer as a media server, anytime you add music or movie to you main computer the files will automatically be uploaded to the mining computer.

I just plugged in VGA-to-Composite converter so it detected presence of "monitor" and allowed using OpenCL :)

Yup, be sure to get one of these. If not, make sure to get a PSU that will have the connector's for however many cards you are using (listed under PCI connectors)

Yes, absolutely.  The drive cage in the HAF-912 comes out completely, thus giving you a lot of clearance and a straight shot from the front fan.  See this video: http://www.coolermaster-usa.com/landing/haf912/home.php?page=features#modular (http://www.coolermaster-usa.com/landing/haf912/home.php?page=features#modular).  I replaced the stock front fan with a high-flow 120 X 120 X 25 mm fan (this one: http://www.newegg.com/Product/Product.aspx?Item=N82E16835705040).

Yes you can. This is what I run: http://blog.zorinaq.com/?e=47

I just used a set of tin snips on mine! :)