Overclocking the CoolFX Ultra/2600 is ideally done with Gainward's ExperTool utility, which is also used to switch to enhanced mode. As mentioned above, this utility overclocks the card to the 450 MHz core and 1200 MHz memory speeds guaranteed by Gainward. However, you can set even higher clock speeds manually. We found that our card had a clock speed limit of 470 MHz core and 1252 MHz of memory. At higher core speeds, there were crashes galore. Also, the computing power dropped noticeably at higher memory clock speeds, which is attributable to the throttling mode so feared by overclockers: this error recognition feature is built in by NVIDIA to automatically throttle performance if there is inconsistent data in the graphics processor.
Below are the detailed results of our overclocking attempts: