I'm just saying that there are some cases where the CPU is actually better suited for particular physics tasks,[/uote]
The only place really where this would happen is on a very limited data set (read one particle at a time) with a very limited set of applied laws of physics applied to them where clock speed would become king. As soon as that data set becomes more complex the mass parallelism of GPU's start pulling away.
even if the majority are much faster on a GPU, and even physx keeps some parts on the CPU rather than offload them (cloth physics does not fall under this category as far as I know).
This isn't just a limitation of Physx but also of Bullet, Havok, etc etc as they are not meant to be 100% real life interaction replication. They are all there for eye candy, nothing more, nothing less. It just happens to be a fact that as that eye candy gets more complex, LIKE the more accurate realworld interaction physics calculation applications out there, a GPU's massive amount of parallelism will thump a CPU pretty much every time if coded correctly.
Physx is for gaming. Nothing more nothing less but a GPU isn't limited to Physx.