ATI Radeon HD 2600 XT

Overclocking

Our 2600 XT sample card runs at 800 MHz core clock and 1100 MHz memory clock by default. The fan speed is dynamically controlled by temperature which makes using this card a very quiet experience. Unfortunately AMD left out the software voltage control mechanism, even though a chip is in place which could control the voltage. The dynamic clock changes (Low/Med/High) from the RV610 cards are not present either which probably explains the high idle power draw.



In the end the card runs completely stable at 857 MHz Core (7 % overclock) and 1143 MHz Memory (4 % overclock). The overclocks are small, but it seems to me that this frequency is not the card's limit but a limit with the card's BIOS or the overclocking software. As soon as you go above this magic frequency the card immediately crashes no matter if it's cold or hot or if the cooling is improved.


Based on the power consumption numbers from the last page it does not surprise that the idle temperature is relatively high and the difference to load is really small. Yet all those temperatures are well withing the operating range of the RV630 ASIC.