Have an x850xt and run perfectly BF2 on all high AA 4x 70-100FPS
Be sure to have properly and complete uninstalled the nvidia driver and to have done a clean install of th eati drivers, (i use the omega driver, they are better without that shit catalyst control center) and have any problems at all.
And if you have already played with your nvidia with the account you are currently playing with the ati, then try to create an offline account and try if the problem persist, i dont know how can i help you.
PS: ATi > Nvidia
Be sure to have properly and complete uninstalled the nvidia driver and to have done a clean install of th eati drivers, (i use the omega driver, they are better without that shit catalyst control center) and have any problems at all.
And if you have already played with your nvidia with the account you are currently playing with the ati, then try to create an offline account and try if the problem persist, i dont know how can i help you.
PS: ATi > Nvidia