Does PhysX scale across the GPU and CPU? If yes, does that mean having a faster CPU enhances PhysX performance or visual quality?
PhysX uses both the CPU and GPU, but generally the most computationally intensive operations are done on the GPU. A CPU upgrade could result in some performance improvement, as would a GPU upgrade, but the relative improvement is very dependent on the initial balance of the system. An optimized PC with the right mix of CPU to GPU horsepower will be the best balanced solution.