Too bad AMD has $500mil more in cash than Nvidia at the end of '07, $1.9b compared to $1.1b.You can be sure Nvidia is also putting significant cash into R&D of this same issue. However, unlike AMD/ATI they have a much larger pool of cash to fund R&D and can afford to contnue investment in R&D Of monolithic GPUs while also funding R&D for multi-GPU.
Also, Nvidia spent about 17% more in all of '07, $554m, on R&D than what AMD spent in Q4 '07, $473m.
Where do you get your data?