I'm thinking of Going Intel and ATI, A nice 45nm dual-core with 3870x2.
Unless AMD fixes up their Phenoms.
B3 steppings will have fixed the TLB problem, among other things.
They should clock to 3GHZ on pretty average air cooling. AMD's already done it before (in a PC they called DAAMIT, which they also used three high-end ATI cards in trifire. I think they might have been HD 2900's though)
Crossfire has 3 different modes like in the review above, for the right task while SLI is just spliting up the screen and letting each video card do its job on each half.
Multi GPU been out forawhile, they should tweak it up some more now.
You can't really do anything to alter the cards that already exist, unless it can be altered by software (i.e. drivers,
maybe firmware). In the case of SLI, I doubt drivers can do much, except for a few minor tweaks here and there (same with Crossfire)
Otherwise, the only thing you can do is release a whole new GPU.
Currently, crossfire seems to scale significantly better - a few times, getting
more than 100% increase.
I might guess that that would be possible because of the higher amount of video ram between the two video cards. But that is just a guess.