user16: GPU mining is the way to go, as at August 2011, until something better arrives on the market. There are plenty of GPUs out there, but only a handful offer the best performance when comparing total number of Bitcoins generated vs. power consumed vs. initial purchase cost of the chip.
Which GPUs provide the best performance in regards to Bitcoin Generation vs. Power Consumption?

user516: In the long term, the lifetime of the hardware may also become a significant factor in calculating the ROI (Return On Investment), especially if technological developments reduce the power consumption to a negligible level.

user27: For price/hash the 5830 and 5850 have been the champs for a while. The 6990 is argueably better because of depreciation... right now it is probably better to buy bitcoins instead of rigs. Or have diversity and split between the two options.

user307: Currently the 5970 is the undisputed champ.  It is much cheaper than the 6990 and offers better performance per watt.  Being a two GPU design it has high density.  Only the 6990 has higher density but that comes with higher capital cost and energy cost.
So
best in terms of Hashes/$ = 5970
best in terms of Hashes/W = 5970
second best in terms of Hashes/system = 5970
The hard part is finding them as they are no longer being produced.

user56: This depends quite  a bit on your cost for electricity. In general, the ATI 6990 (758 MH/s) is fastest, but it consumes quite a bit of energy. The ATI 5970 (655 MH/s) runs at 86% of the speed of a 6990, but consumes less power. If you have a limited number of slots on your motherboard with cheap electricity, choose the ATI 6990. If you have unlimited PCI-E slots and relatively expensive electricity, choose the ATI 5970.
NOTE: There is no such thing as "free" electricity. Someone is paying for it. If you believe you have free electricity (i.e. a dorm) it is likely that someone is paying a cost for that power.
https://en.bitcoin.it/wiki/Mining_hardware_comparison

user14: According to https://en.bitcoin.it/wiki/Mining_hardware_comparison the best GPU in regards to power consumption is the 5970, the tricky part is finding one of those for sale.

16: <p>GPU mining is the way to go, as at August 2011, until something better arrives on the market. There are plenty of GPUs out there, but only a handful offer the best performance when comparing total number of Bitcoins generated vs. power consumed vs. initial purchase cost of the chip.</p>

<p>Which GPUs provide the best performance in regards to Bitcoin Generation vs. Power Consumption?</p>
 516: <p>In the long term, the lifetime of the hardware may also become a significant factor in calculating the ROI (Return On Investment), especially if technological developments reduce the power consumption to a negligible level.</p>
 27: <p>For price/hash the 5830 and 5850 have been the champs for a while. The 6990 is argueably better because of depreciation... right now it is probably better to buy bitcoins instead of rigs. Or have diversity and split between the two options.</p>
 307: <p>Currently the 5970 is the undisputed champ.  It is much cheaper than the 6990 and offers better performance per watt.  Being a two GPU design it has high density.  Only the 6990 has higher density but that comes with higher capital cost and energy cost.</p>

<p>So
best in terms of Hashes/$ = 5970
best in terms of Hashes/W = 5970
second best in terms of Hashes/system = 5970</p>

<p>The hard part is finding them as they are no longer being produced.</p>
 56: <p>This depends quite  a bit on your cost for electricity. In general, the ATI 6990 (758 MH/s) is fastest, but it consumes quite a bit of energy. The ATI 5970 (655 MH/s) runs at 86% of the speed of a 6990, but consumes less power. If you have a limited number of slots on your motherboard with cheap electricity, choose the ATI 6990. If you have unlimited PCI-E slots and relatively expensive electricity, choose the ATI 5970.</p>

<p>NOTE: There is no such thing as "free" electricity. Someone is paying for it. If you believe you have free electricity (i.e. a dorm) it is likely that someone is paying a cost for that power.</p>

<p><a href="https://en.bitcoin.it/wiki/Mining_hardware_comparison" rel="nofollow">https://en.bitcoin.it/wiki/Mining_hardware_comparison</a></p>
 14: <p>According to <a href="https://en.bitcoin.it/wiki/Mining_hardware_comparison">https://en.bitcoin.it/wiki/Mining_hardware_comparison</a> the best GPU in regards to power consumption is the 5970, the tricky part is finding one of those for sale.</p>
