The performance we experienced is a bit unexpected. We figured that GeForce GTX 580 3-Way SLI would compete much stronger with and in some comparisons dominate AMD Radeon HD 6990/6970 CrossFireX "Tri-Fire" performance, especially when you consider that three GeForce GTX 580 video cards cost between $475-$555 more than our Tri-Fire configuration. With that kind of cost difference, GTX 580 3-Way SLI needed to eclipse AMD Tri-Fire gaming performance, but 3-Way SLI did not.
In fact, the best case was that GTX 580 3-Way SLI matched Radeon Tri-Fire performance. In none of these games did the average framerate of GTX 580 3-Way SLI exceed that of AMD Radeon HD 6990/6970 CrossFireX. This is bad news for the GTX 580 3-Way SLI folks, considering the Radeon HD 6990 wasn't even running in its OC performance mode. On top of that, three separate Radeon HD 6970 video cards offering triple-GPU performance will be faster still since those have faster core clock speeds and faster RAM speed than what we tested here.
We have given every advantage to the GeForce GTX 580 3-Way SLI configuration in this evaluation, and yet it still can't compete. We are testing with the "slowest" Radeon 6990/6970 Tri-Fire configuration possible in this $1000 price range, and GTX 580 3-Way SLI just can't touch it.
The Bottom Line
AMD Radeon Tri-Fire is giving you the same or better performance than GTX 580 3-Way SLI for $500 and 200 watts less. You get both a money savings and a power savings using Radeon 6990/6970 Tri-Fire instead of GeForce GTX 580 3-Way SLI.
It just makes no sense to build a GTX 580 3-Way SLI currently. AMD Radeon 6990/6970 Tri-Fire is better in terms of value, efficiency, and gaming performance than GTX 580 3-Way SLI. If you want to utilize that performance, the 2GB of RAM per GPU on the Radeon HD 6970 will allow you to do this and provide a noticeable gameplay experience and visual improvement over GTX 580 3-Way SLI. No other conclusion can be made at this point, AMD Radeon HD 6970 Tri-Fire is a tremendous value compared to GTX 580 3-Way SLI, and Tri-Fire is the better choice for multi-display gaming.
Given NVDIA's history of excellent SLI scaling, we expected to see the GeForce GTX 580 3-Way SLI dominating AMD Radeon Tri-Fire. Instead, this review has only further reinforced what an incredible value AMD's current generation video cards really are.