My heart's in the Highlands, my heart is not here - Robert Burns
Tagan's mathematics proposes that two SLI 8800 GTX need 450W together or 2x75 W for PCIe slots, and four times 75W for additional six pin connectors, two per card. If you want to play with RAID you need some extra power as well.
So Tagan decided to offer TG-1100 (TG-1100-U96 1100W. It can even power Quad graphic machines if anyone launches one.
The only problem I see is that we managed to run a Geforce 8800 SLI setup on high end Intel and AMD machine with a 750W PSU. You probably need 1100 for bunch of drives and more than two cards but we don't think it's a necessity, yet. ยต