[fpgaminer], [li_gangyi], and [newMeat1] have been working together for the last few months to build an FPGA bitcoin miner that blows GPU mining rigs out of the water in terms of power efficiency. The board requires only 6.8 watts for 100 Mhashes/second, but [li_gangyi]’s blog says the team expects to hit 150-200 Mhashes with some improvements. That’s efficiency GPUs can’t touch.

Bitcoins are a digital currency that are ‘mined’ by calculating hashes that verify bitcoin transactions. While mining operations can be performed on a CPU, graphics cards and FPGAs beat CPUs by several orders of magnitude in terms of how many hashes can be performed per second.

The heart of the board is a Spartan-6 LX150 FPGA – a pricey bit of kit – and the team is selling each board for $440 USD. For that amount of money, you could buy two ATI 6770s at half the price and crunch four times as many hashes a second. At less than 7 watts, though, we wouldn’t worry too much about cooling the rig and the electricity costs will be very low.