SLI or crossfire for that matter is just a white elephant.
its just the different graphix companies showing what they can do with limited tech.

no one is dumb enough to buy that stuff unless they got lots of money and dont know what they are talking about.

sats show that the mother board and CPU gets bottle necks of info, and thats what slows the system down (with a high-end graphics card).

its silly buying 2 x SLI 7900's when theres directx 10 just around the corner.

all the above stuff hasnt got any progs to take advantage of the tech anyway.