The guys at the [H] take a look at running not one, not two, not three, not four, but all of the above 98xx series cards in a rig to see if SLi has a point of diminishing return. The one table that sums it all up for me is the power consumption. Insane.

"If you are looking for the absolute highest framerates, 3-way SLI will provide this, but it will not allow you to improve your gameplay experience in some games, so you are paying extra money for nothing unless you want the performance for canned benchmarks."