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Power supply wise I recommend at the very least, 600 Watts. You might not utilize all that power distribution, yet especially in this high-end game make sure you have some reserves folks. You do not want your PSU to run at it's maximum all of the time. See, it's not that your PC will consume that much power, it's just that you want to make sure your PSU can deal with the hefty load and will stay stable during you entire gaming experience.
Please make note of the fact that the card uses one 6-pin PCIe power connector and one 8-pin connector.
Inevitably people will opt CrossfireX and go with a 4-GPU based model. With two cards obviously 1000+ Watt power supplies are recommended, and in fact even needed to be able to even supply something as simple as enough PCIe graphics power connectors. We passed 700 Watts, which is just too much to play games folks. We used a Galaxy 1000 Watt DDX PSU by the way, perfectly stable.