There's a 39% increase in performance with 8X AA enabled at a resolution of 2560X1600 for 3-Way SLI in this test versus standard SLI

Guru3D and HotHardware have posted NVIDIA 3-Way SLI GeForce 8800 Ultra Performance Preview. Here's an excerpt:

The requirements for a 3-Way SLI setup are fairly straight-forward. You can easily build one of these monster configurations yourself and annoy your friends at National Grid and Keyspan in the process too. All you'll need is an 1100 Watt power supply with at least six 6-pin PCI Express power connectors or four 6-pin and two 8-pin connectors, an nForce 680i or 780i motherboard with three full-length PCIe slots, a fairly roomy case with good airflow, Windows Vista and the right NVIDIA driver to support 3-Way SLI. Incidentally, NVIDIA has noted that AMD-based 3-Way solutions are forthcoming. We'll take a look at what a 3-Way SLI-enabled system from the folks at MainGear Computers looks like next.

The Maingear system we tested here today, based on NVIDIA GeForce 8800 Ultra 3-Way SLI technology, showed significant performance gains that scaled relative to its additional graphics processing resources, in specific test setups and gaming usage models. Under test conditions with virtually all game engines we tested thus far, running 3-Way SLI at 1920X1200 or lower resolutions with less anything less than 4X AA, offered little or no performance gain. It was at 1920X1200 or 2560X1600 resolution with either 4X, 8X AA enabled that we reported a performance increase of around 40% with 3-Way SLI versus a standard two cards SLI setup. We would also offer that once we have access to the forth-coming patch for Crysis from Crytek and Electronic Arts, that we could very well see sizeable gains there also. Conversely, the power consumption of this system exceeded anything we've seen here in the test lab to date by a wide margin, topping out in excess of 800 Watts under full load.

So, what's the moral of our little 3-Way SLI story that we've layed out for you today? Do you need 3-Way SLI? Well, that depends on your perspective. There's no question that a 3-Way SLI setup will benefit end users with 30" LCDs that want to run at their monitor's native resolution with a high level of image quality processing turned on as well. At the end of the day, we were rather impressed that the NVIDIA 3-WAY SLI solution scaled as well as it did at these extreme high resolutions and IQ settings.