It's just a suggestion not a must. If you have performance that isn't to your liking, it is something to think about in the future. There are really good aftermarket air cpu coolers for $55 or less. I paid about $25 dollars for mine after shipping. Just changing the PC case I was using dropped my cpu temps by 9C.
I have another doubt about that when i use 8800GTS 512 for PhysX it also supports for CUDA.and can i use for GPU based Programs
I have Bottle neck problem with HD 5850.
only 10200 GPU score in Performance Preset.
How to solve this Problem can adding PhysX Solve