Originally Posted by Euphobia
Wouldn't the 470 be able to handle physx itself though better than what the 8800GTX dedicated could?
They made the 275 with the 250 for pysics because the GPU has a hard time doing both and cannot at the same time and I quote(or paste in this case)
Optimizing PhysX performance
PhysX can run on the same GPU that's performing rendering, but the performance will be sub-optimal. This is because the GPU can't run PhysX and render your graphics at the same time: when PhysX calculations need to be performed, a "context switch" from rendering to CUDA must occur, and another context switch is required when switching back to rendering.
Although these context switches occur very quickly (on the order of microseconds), they also must occur very frequently, and the context switching time extracts a noticeable performance penalty (one of the performance advantages of NVIDIA's forthcoming "Fermi" architecture is that context switching is much faster). Context switches take so much time that PhysX running on a relatively low-end GPU that's dedicated to the task will handily outperform PhysX running on a high-end GPU that's also performing rendering.
I will be installing the 8800GTX just for physx and will let u know how it goes.