Bitcoin Forum

http://secure.newegg.com/WishList/PublicWishDetail.aspx?WishListNumber=23890188

Here's my masterpiece. I paid 1000 for it, it's extremely reliable and wont blow up, no dual PSUs, great cooling,
great overclocking, can be used for extreme gaming if you use a crossfire bridge. No cheap garbage, extremely resaleable
if the bitcoin market crashes, takes 44 days to pay for itself(at $0.20/kWh) if bitcoins are still worth 20usd/btc.

Oh yea, I forgot to introduce myself. I have been building computer rigs for a decade now(remember the Pentium 4?) and I have many industry certifications in the computer field.

Ever since I learned about this bitcoin thing and mining, I knew it was my chance to finally put my skills to the test and build for profit. That rig you see in the above post, took me 10 minutes to build and about 2 hours to order at the best prices through newegg, ebay, and mwave. For those who want a good deal, try auctionsniper, I got those video cards at the normal prices on ebay.

did you calculate with changing difficulty? because i think 44 days is a bit fast

Oops, my new estimate is about 80 days based on the fact that more and more power
is being added to the network. I am hoping that difficulty growth tapers as the video
card market dries up.

Forgot to add ram to that wishlist. You probably wouldnt need any if you had some laying around.

Do people take into account bitcoin value increases?  For example, if the value of the coins increases 1% per day and the difficulty increases 1% per day, then they cancel.

yeah but the change in value cannot be foreseen.
the only thing that (nearly surely) gets higher is the difficulty (it can get lower, but that is not very likely atm), so you can just speculate about the value.

Right.  For as long as the payback from mining is higher than the cost of mining, the number of miners will increase.

Essentially, the difficulty should track the price.  As the price of a bit coin rises, more and more processing power will be added to the mining network.

It will be interesting what happens with the jump from 50 bitcoins per block to 25 bitcoins. 

In theory, the difficulty should drop since lots of miners will leave.  However, since they have already paid for their mining rigs, they might just continue to mine.  The effect would be for the difficulty to flat-line or maybe drop slowly.

If the payback from mining is more than double the cost of mining, then dropping to 25 will mean that it is still worth it for miners to continue and more processing power would still be added (but probably more slowly).

You could save yourself $100 and increase cooling by skipping the case completely and letting the system run open-air.  I believe one guy on these forums used zip-ties to suspend his GPUs above his motherboard, connecting them to a cheap, wire shoe rack.  Sure, it's not pretty, but it is efficient, economical, and will run cooler.

The Newegg HD 5830s are out of stock and will probably remain that way.   I went with six overclocked 5770s on three motherboards and am happy with 1200 MH/sec drawing 860 watts from a shared UPS.

I chose a case because I want to have the option to resale the rig to anyone very quickly in case the market crashes. As for cooling, you are right about going no case at all, you have no heat build-up. And as for case cooling, that case I chose is horrible for GPU cooling. I ordered it and realized that it does not have a spot for a dedicated GPU fan. So, I am going to use my current case which is an antec 1200(http://www.newegg.com/Product/Product.aspx?Item=N82E16811129100) and it will be capable of pushing out all that heat. I am not a fan of going caseless, because over a shorter period of time, dust will build up onto your CPU and especially GPU heatsink making maintainance sort of a headache. But hey, there are pros and cons, it's a personal choice.