The lucky chaps from DailyTech got a review sample of the GeForce 8800 today and they write it's pretty big and has hefty power requirements.
The GeForce 8800 comes in two flavors, which we will get into more detail about over the course of the next few days. Both cards are dual-slot PCIe cards measuring a little less than nine inches in length. The first card, the GeForce 8800GTX, is the full blown G80 experience. The GeForce 8800GTS is a cut down version of the first.
The marketing material included with the card claims NVIDIA requires at least a 450W power supply for a single GeForce 8800GTX, and 400W for the 8800GTS. Top tier vendors in Taiwan have already confirmed with DailyTech that GeForce 8800 cards in SLI mode will likely carry a power supply "recommendation" of 800W. NVIDIA's GeForce 7950GX2, currently the company's top performing video card, carries a recommendation of 400W to run the card in single-card mode.