-Motherboard: Msi Big Bang XPower
-CPU: Intel i7 950 Bloomfield
-GPU: Ati Radeon HD 6870 in 2x Crossfire
-RAM: 2 x 3GB Adata Gaming Series
-HDD: SATA II Western Digital Caviar Black 1TB
-DVD+DVD RW drive
-Internal BluRay Player
-2 Cold Cathodes
-3 120mm fans
-2 180mm fans
I decided to go with the Radeon GPU's because the 400 series Nvidia cards take up so much power and run so hot, and I can't afford the 500 series. Maybe when the 600 series comes out I'll switch to that.
Good lord will someone rip that list off the internet. Getting tired of seeing something so wrong.
Look at the link that Psycho posted. A SYSTEM with a 6870 playing Crysis only needed 277W. Another 6870 should add at most 150W. This means any PSU that can output 425W (36A) on the 12V rail(s) will be fine. My old Antec EA500W can do 34A, so I would think any of the newer 550-600W units will be fine. You should make sure that it has all the plugs it needs to run both cards.