Your sort of right about the money vs performance sort of being unfair. I'll give you that. The original OP however asked that and people chimed in. That's why I showed the AMD 6990 now being compared to slightly less performance than two GTX 570's two post above even though it was sort of off topic.
Now your benchmarks video also shows some substance. Good job. Another solution offered but this thread isn't "What beats the GTX 580 SLI". We're just staying on topic. At least now when you find a thread asking what beats two GTX 580's you can post back with credibility. Let's call a truce and stop this bantering.
P.S. The original poster has a 850 watt psu. He can't run the AMD 6990 and a AMD 6970 so that solution won't work for him. However he can choose between one AMD 6990 or GTX 580 SLI with just enough power. So for his situation I can understand his post question. He's got to decide if paying an extra $250 is worth the extra performance.
In his case he could also buy two GTX 570 SLI and have just a tad more power for the same amount of money. He would get to decide if he wants a dual gpu or two single for his power supply.