Be advised and consider this as the rumor-based speculation it is. A lot of information is circulating right now and this is just a summary of it. Tri-SLI is in testing and seems to be working well at this stage. It will be limited to the high-end cards GeForce 8800 GTX and GeForce 8800 Ultra due to the physical need of a three-slot dual-lane SLI bridge. The PCIe 1.0 bandwidth of nForce 680i just isn’t enough at the time. Things may change with the coming PCIe 2.0 compatible 7 series chipsets, but nothing is for certain at this time. We certainly hope that it will be possible to use the GeForce 8800 GT in Tri-SLI. To us that actually seems like the most sensible Tri-SLI setup, considering the price/performance ratio.
Exact performance scaling figures are not here yet, but some birdies say the third card will add almost as much as second card does to a dual card SLI setup. Partners are said to be pleased with the scaling at least. Working drivers were distributed a few weeks back and are improving nicely as we close in on the launch sometime next month, might be sooner.
Tri- and QuadFire are not suppose to be limited to any card of any sort, just keep them all in the same range; all 2400 cards, 2600 cards, 2900 cards and so forth, and you should be good to go. Mixing of cards from different series is a consideration for the future, but doesn’t seem to be of high priority today.
CrossFire is not built to be high-end exclusive but to work with pretty much any graphics chip made by ATI, and then just multiply them in numbers. The performance scaling is suppose to be excellent, with the third and fourth card adding as much as 80% per card in certain applications. That particular figure is not something I would trust my life with, but was deliver together with other statements that were quite realistic. I just thought you might wanted to see it.
To summarize, 3-way SLI seems to be a high-end exclusive arrangement, at least to begin with. The increased bandwidth of the PCIe 2.0 compatible nForce 780 might change that. Tri- and QuadFire should work with cards from all price ranges, just as long as they match. Right now CrossFire seems to be the better scaler, but as there is a lot of software development involved and we all know the reputation ATI has when it comes to making drivers (not implying anything more than the exact words) we should really just wait and see what happens.
