The PPU won't make any difference for SLI. If a game still has tons of really big textures, complex static worlds, high poly models, normal maps etc... then dual video cards will still help. The PPU is for physics alone, nothing else. And I actually read in an article that it will process up to 50,000 phyisal objects with ease. Also, I thought I read somewhere that ATI liked the idea of a PPU and actually is thinking about putting a PPU chip on their graphics cards.