Help me ! How to build a PC for bitcoin mine ?

[worldinacoin]

I would use a refurnished PC and put in as many second hand graphics cards that I can, a new one seems to be difficult for ROI

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[johnb210]

I say go for the 6870.  I don't know where people get their prices, but if you find a deal like http://slickdeals.net/forums/showthread.php?t=3293164 you can get a 6870 for $150 after rebate, and even sell the free games for another $25 back or so.  I'm getting 290 MH/s with my 6870, and it only draws about 140 W (according to my kill-a-watt) above my baseline system, so you could probably even do two of them on your power supply.

Based on that 290Mh/s at $150, that's 1.933 Mh/s/$, and more than 2.07 Mh/s/watt, which is just about as good as I've seen for any card combination if you just want to do some basic mining with a regular PC.

Everybody else - please let me know if you're actually getting super deals on used 5XXX cards, I just haven't been able to find them.

[mizike29]

Well the ATI 6990 I have gets 800 MH/s and with two I get 1640 MH/s which is really where you need to be to make bitcoins right now with the difficulty but electricity is tough, if you got free electricity then the 6990 is worth it for the hash rate alone and its only going to get harder to make bitcoins.  If on a budget then u have no choice but to go lower.  The 6950 gets 450MH/s  and 6870 gets 340 MH/s.  I personally would not go any lower then that and or just buy the best highest MH/s Card you can get.   This website actually helps alot, and will show what you can expect from a card   https://en.bitcoin.it/wiki/Mining_hardware_comparison

[worldinacoin]

Well 6990 is sure good but how long do you expect to break even? What is the ROI?

[mizike29]

Well I started about a year ago so I am good for mine, but yeah as prices are now, it would take a while, but you still have a bad ass card, gaming and resell value in the card plus there hard to get, so even months down the road you could still get a good price back for the card if need be.  But there are ones less price vs mining that might get payed off, but still a long ass time for even 300 bux in bitcoins.