9800GX2 and X48

[bellinghamwa]

Teh 9800GX2 will be faster because it has 2 cores to process the data vs 1 on the 8800Ultra. The benefit of SLI isn't to increase your memory because you don't (as was explained to you above) but to increase your GPU rendering power.

But what about the regular 9800GTX (not GX2). Could the 8800GTX Ultra (768MB and 384 bit) potentially outperform a 9800GTX (512MB and 256bit)?

I don't understand why NVIDIA is limiting cards to 512MB if some games will use as many 750MB.