Dual ATI Radeon HD 6990 setup

[Gullanian]

Hi guys,

I'm considering buying a setup for number crunching on the GPU, a bit of research shows me that HD 6990 are best for number crunching in my case.

The PC will not be used for anything else. Everything else has to be as small a cost as possible. Can anyone suggest parts for me? What bottlenecks do I need to watch out for?

So I'm building this a weird way round, I'm starting with 2 HD 6990's!

Thanks for your help

Tom

 

[Gullanian]

Never installed water cooling before, but I have a friend who does it a lot who could help.

Noise isn't a problem, I have a spare room to put it in. There is the possibility I might be running more of these machines as well.

At room temp with a decent case, how much of a risk is this cooling problem?

 

[Gullanian]

Hi guys thanks for the info, it's mining bitcoins, I've talked to a few more people, run some more numbers and unfortunately it's going to be too risky of an investment at this late stage in the difficulty. Unfortunately hardware prices in the UK are just too expensive comparatively, and the same with electricity. I was considering raising some capital really quickly and buying 3-4 of these machines to get set up this week.

http://www.alloscomp.com/bitcoin/calculator.php

With 1440 megahash p/s (roughly the rate of 2x6990) it would yield around $50 a day at current prices, minus $8 electricity (£3+other hw) would mean $42 a day. The setup is going to cost >£1k just for the cards, probably another £500 to get it going. So ~£25 a day would take 60 days to break even, if the BC to USD exchange rate of $20usd/bc remains relatively stable (no big drops).

Also the difficulty level is rising very fast. I've been told I've missed the boat pretty much. If I had one of these cards or a comparable one I'd be mining with it. My 5570 (I think!) can crunch 10% those speeds, = $5 daily, just not enough to be worth it. Requires serious GPU power.