Overclocking
To find the maximum overclock of our card we used a combination of ATITool's successor and our benchmarking suite.
The overclocks listed here were achieved with the default fan and voltage settings as defined in the VGA BIOS. Please note that every single sample overclocks differently, that's why our results here can only serve as a guideline for what you can expect from your card.
The final overclocks of our card are 925 MHz core (9% overclock) and 1110 MHz Memory (14% overclock). AMD has been promising that a large portion of HD 4890 cards will be able to hit 900 to 950 MHz, apparently we didn't get lucky very with our samples. The Sapphire card tested here managed 925 MHz and our second card from PowerColor managed 880 MHz.
Using these clock frequencies we ran a quick test of Call of Duty 4 to evaluate the gains from overclocking.
The actual 3D performance gained is 8.8%.
Temperatures
Temperatures are in a perfectly safe range, I would have wished for less fan noise and slightly higher temperatures though.