After MUCH discussion (whic Follows) I think it can be said that these cards are DEAD EVEN. What brings about this assessment. The extensive benching done by notebookcheck shows its recorded as a 5% edge to the 580 SLI ... however if you actually do the math on their posted FPS rates, the difference is 1.1% edge to the 580. Some others, including myself, have noted that notebookcheck didn't bother to turn on overdrive for their testing (something I think is akin to getting in your car, putting it in Drive instead of overdrive and getting on the highway) Overdrive increases the performance of the 6990 between 5-10%. With overdrive on the 6990 MIGHT have a slight edge over the 580. (but no one has done the testing to back this up) All in all, if you take the NBC benches at their value there should be a 1.1% difference, on some games the 580 will win, on some they will be dead even and on other the 6990 will win. We will call this match a DRAW ! Enjoy the cards you have, if you prefer one interface over the other, all the power to you.