In all honesty I'm wondering HOW THE HELL they have a 1200W PSU running that. Each card uses 275Watts, 4 of them use 1100Watts (Or 110A on the 12-v Rail (The Corsair 1,000Watt provides 83), an overclocked CPU (You will need one!) uses 150Watts, and 15A. So you need AT LEAST 125A on the 12-v rail.
Now now, I know adding cards in SLI doesn't double the wattage. But it'll come close. Reeeal close.