I recently bought an hd 5770. Before installing the driver, I checked cpu-z (graphics tab) and it showed 849MHz core clock and 1200MHz memory clock. After installing the latest ATI driver, I checked again and saw the clocks dropped to 157Mhz and 300 Mhz respectively. Can somebody explain this to me?
When the cards aren't being used to their full potential, they are put into 'idle mode,' which severely drops the clocks so that it uses less power and radiates less heat. Load up a game and see what your clocks are then.
I think its ok and there is nothing to worry ,All graphics card drops its memory and clock speeds at idle to save energy ie to reduce power consumption,So when you game or do anything which requires graphics it will automatically raise its clock speeds .