In our original evaluation, every game we tested was a certain percentage faster on the AMD Radeon HD 6990+6970 Tri-Fire setup. With performance like that, we came to the conclusion that the $500 more expensive GTX 580 3-Way SLI setup was not a good value.
In our redux today, using our new 4.8GHz CPU, GTX 580 3-Way SLI has come out of its hibernation and is peeking around its fort ready to lay aim on the first prey it sees. That prey happens to be AMD Tri-Fire. In all of our testing today, the GTX 580 3-Way SLI setup performed faster than AMD Radeon HD 6990+6970 Tri-Fire, except for Dragon Age II.
Depending on the game, it wasn't just a small victory either. In F1 2010 there was nearly a 30% performance advantage with GTX 580 3-Way SLI over Tri-Fire. In BC2 there was a 24% performance improvement over Tri-Fire. However, there was equally some unimpressive differences, such as Metro 2033 with 6% and Crysis: Warhead with 7%.
What it looks like to us is that the more shader intensive games like DA2 and Metro 2033 and Crysis: Warhead have the least performance advantages. The CPU can only do so much, and while it opens the taps on the GTX 580 3-Way SLI setup, ultimately it is down to the GPUs for performance at these resolutions with these titles.