Hello
It seems ATI cards are limited in speed with ClOD. (eg 500MHz on a 4890 usually running 870MHz)
Also ATI users do not see much of an improvement in the BETA patch.
This poll to see if this is always the case or not.
In order to answer , you can measure core GPU speed using GPU-Z (using export to text file function, or graphs)
NB: when clock speed is limited , it can be overcome by several methods.
I did so using ATI tray tools, "overclocking" my card to the 870MHz speed. And game is playable again
