Cheapest rig for cross fired 5870's

Gullanian · 14 Jun 2011 at 00:13

I want to cross fire 2 of these to run at 100% days on end:

http://www.overclockers.co.uk/showproduct.php?prodid=GX-147-XF

Is my BeQuiet 650w PSU good enough for this?

Also, what is the cheapest Mobo I can buy that will fit these cards and a AMD 1090T x6 Processor?

Thanks for the help, would love to order this tommorow.

Gullanian · 14 Jun 2011 at 00:24

Surveyor said:
Don't you ever sleep?

Or are you still Bitcoin mining?

My sleep pattern is rubbish, I have trouble sleeping sometimes! I found out these cards give excellent £/BC rate, better than most other cards which makes it within the realms of decent profitability if I get them quickly.

Gullanian · 14 Jun 2011 at 00:25

Thanks for comments will look at them properly tommorow!

Gullanian · 14 Jun 2011 at 00:40

http://bitminer.info/ (figures quite under what can be achieved with some basic OC afaik)

I have a solo 5770 at the moment which works at a rate of 170mhash, overclocked this can go to 190mhash but I'm not too good at OCing and it's unstable but with some skill I'm sure you could get it to 200mhash.

I've heard that a 5870 can do 400mhash/s, 2 of them = 800 mhash/s.

Check out here:

http://bitcoinx.com/profit/

Electricity wise you're looking at £1.50-£2 a day. A 5870 can do ฿0.56 a day, 2 of them + OCing = ~฿1.20 a day.

BC is currently worth ~$20 each, (https://mtgox.com/trade/buy), I'm also gambling a bit that the value is going to increase as well, I'm trying to gain BC for medium term investment (~4 months or so).

So at $20 each you are earning ~$24 a day, minus $4 a day in elec = ~$20 clear profit. Cards are ~$400 total for 2, which means in 20 days they pay for themselves (and they have obvious resale value).

Gullanian · 14 Jun 2011 at 00:40

Surveyor said:
The OP was considering dual 6990's

Dual ATI Radeon HD 6990 setup

Yeah I was, just can't quite pull the trigger it's over extending me too much, I think 5870 is a good compromise.

Gullanian · 14 Jun 2011 at 00:46

Dual 6990s should be able to pull B2.50-3 a day which is phenomenal, ~$50 a day at current rates. It's just going to take ~50 days to pay them off which is too long a time frame for me for that cost. Also, they are in short stock in a lot of places (especially USA apparently) for the specific reason of bitcoin mining.

Gullanian · 14 Jun 2011 at 00:52

http://bitcoinx.com/profit/index.php

Difficulty : 434883.00
Hash rate: 800000 (2x5870)
$1k setup cost
$0.30c p/h electricity
$20 conversion rate

= 30 day break even

So tempting just to buy this right now, I think I'm going to have to just go for it.

Gullanian · 14 Jun 2011 at 00:54

By the way, if Bitcoins crash which isn't out of the realms of possibility, look out on ebay for an influx of discount 6990's.

Gullanian · 14 Jun 2011 at 02:10

stulid said:
Is this bitcoin thing for real? what data are the cards crunching to make money?

Yes, it's real, but you might be buying into a greater fools theory:

http://en.wikipedia.org/wiki/Greater_fool_theory

Too early to tell.

Check MtGox.com for market prices, those are live actual prices you can trade BitCoins for USD. It's extremely volatile.

Gullanian · 14 Jun 2011 at 02:29

I admit my knowledge here is a bit hazy but as far as I know it's double SHA256 hashing a block header as part of a process of block generation.

We have mentioned in the previous section that adding a block to the block chain is difficult, requiring time and processing power to accomplish. So what incentive does anyone have to spend the effort to produce a block, if it takes up all these resources? The answer is that the person who manages to produce a block gets a reward. This reward is two-fold. First, the block producer gets a bounty of some number of bitcoins, which is agreed-upon by the network. (Currently this bounty is 50 bitcoins; this value will halve every 210,000 blocks.) Second, any transaction fees that may be present in the transactions included in the block, get claimed by the block producer.

https://en.bitcoin.it/wiki/How_bitcoin_works

Gullanian · 14 Jun 2011 at 08:37

How does this look?

XFX ATI Radeon HD 5870 1024MB GDDR5 PCI-Express Graphics Card

Sapphire Pure CrossFireX 890GX (AM3) Motherboard - Retail

Corsair Enthusiast Series TX 650W V2 High Performance Power Supply (CMPSU-650TXV2UK)

AMD Sempron 140 2.70GHz (Socket AM3) Processor - Retail

Corsair Value 2GB (1x2GB) DDR3 PC3-10666C9 1333MHz Low-Voltage Single Channel Module (VS2GB1333D3)

I have a case + HDD's spare. Still a bit too expensive @ £520

Gullanian · 14 Jun 2011 at 09:37

Yeah why not try it, it took me about 45 mins to set it up mining, lots of guides out there, give it a go. I recommend you join a mining pool (removes the variance, gives you steady payouts, look at Slush's pool)

Gullanian · 14 Jun 2011 at 11:00

I quite like the BC advocates arguments against it being a bubble, I mean cash also has no intrinsic value either does it?

Gullanian · 14 Jun 2011 at 11:18

My 5770 is running today as a test, ~2 hours it's generated 0.03BC which is around $0.60 worth. It's not much but it's definitely more than the electricity.

Gullanian · 14 Jun 2011 at 11:37

Expansion slots:
1x PCI Express x16 slot (PCIEX16)
1x PCI Express x16 slot (PCIEX8)
1x PCI Express x16 slot (PCIEX4)
2x PCI Express x1 slots

That mobo, I don't know too much about HW, is it possible to have more than 2 5870's? Can I have 5 cards in it? Would it work?

Gullanian · 14 Jun 2011 at 12:03

Should that one fit 3 comfortably? I'm thinking buy that mobo and 3, then buy more at as soon as I know if they can fit or not. Thanks for all your help btw

Gullanian · 14 Jun 2011 at 12:46

Yeah I can run multiple instances of the generator client on the machine, the client allows you to do this. If it doesn't there are ways as other people have done it with 4 cards apparently.

Ok just speccing it all up now see if I can do it

Gullanian · 14 Jun 2011 at 12:54

Look good?

Should perform 1ghash/s

Gullanian · 14 Jun 2011 at 12:55

cmndr_andi said:
Yes, that 990FX UD5 board will pretty happily fit three dual-slot cards (like the 5870). You would install them in the 1st, 3rd and 5th PCIE slots and they should run at PCIE v2.0 x16, x8, x8 speeds respectively. x8 speed really doesn't bottleneck the 5870 much, this review concludes the performance drop is very small compared to a full x16 speed slot.

That said, with three cards installed in that board, they will be right on top of each other, which will mean that for 24/7 mining you will need to manually crank up the fan speeds to keep the cards cool. If you want to go with a board with more spacing for cards, then you could go for a pentium s1155 cpu and a sandy bridge board like this XL-ATX MSI Big Band Marshall - however - it is quite a bit more expensive.

Can that board hold 8 double thickness cards? Or probably only 4?

Gullanian · 14 Jun 2011 at 13:02

Nah it's too expensive anyway, sticking to the one you suggested I think. I'm really torn as to if to buy this or not. Need to decide by the end of the day.

I wish 6990's were in stock, part of the reason I want to do this is have a shot at earning the hardware for free, owning 1 or 2 6990's is better than owning 3 5870's which are pretty much useless outside the scope of mining for me. 1 6990 has a lot of utility afterwards (future proof) as well as better resale value.