Which power supply should i buy?

I've never had a occasion to need 1200W of power for any computer I ever built, so it would be hard to say. Corsair has one of the best ratings for PSU's and CoolerMaster is no slouch either! I'd spend the extra bucks on the Corsair. Unless your rig is using at least 3, GTX 580's you really don't need that much power! IF you have a Case that has upper and lower PSU locations you can use two lesser PSU...one to drive the machine and one just for video cards. I have a wacko client that uses a Corsair 650W for his machine an one 850W for the video cards!