PC-magazine reviewed a few high end machine, including the new Falcon NW Mach V which uses a 3.6GHz Xeon with dual Nvidia Geforce 6800 Ultra in SLI configuration - it scored 20,429 in 3DMark03 default settings.
Link
This means that SLI almost doubles the graphics raw power of a machine, but if you look at real world performance (fps), for example in doom 3, the main thing is that it stays high (above 60 fps) even on the highest settings @16x12, which is 50% higher then the closesst non SLI machines (including FX-55's).
I hope that's enough to shut up all the people that doubted SLI.
Link
This means that SLI almost doubles the graphics raw power of a machine, but if you look at real world performance (fps), for example in doom 3, the main thing is that it stays high (above 60 fps) even on the highest settings @16x12, which is 50% higher then the closesst non SLI machines (including FX-55's).
I hope that's enough to shut up all the people that doubted SLI.