Below is the specification for the system that I am having.
Phenom II X4 955 @ stock
4 GB of RAM DDR3 (1600 MHz)
Radeon HD 5870 @ stock
With system also my computer is running very slow. I have already tried with the 11.5a Catalyst but there is no improvement in the FPS. Earlier to this, I was using the 11.3. I think that most of the AMD/ATI users are having the same problem with this. So please tell us that what is the reason or solution for this problem.