ATI Radeon HD 2600XT picks a fight with Nvidia's Geforce 8600GT based card. Both Jetway HD 2600XT and Zotac 8600GT Zone kept the reference clocks so that we can get a realistic result in testing these two cards.
HIS HD 2600 XT IceQ is overclocked, which makes it the winner of 3DMark tests. Radeon HD 2600 Pro is slower than Geforce 8600GT, but much better than Geforce 8500GT.
Overclocking wasn't that hard, at least when you overclock the GPU. We managed to get HD 2600 XT from 800MHz up to 911MHz and HD 2600 Pro went all the way up to 867MHz. When you compare these results with reference clocks, HD 2600 Pro ends up being a better overclocker. We managed to get 44.5 per cent GPU overclock from HD 2600 Pro while HD 2600 XT had a 13.8 per cent boost. Nevertheless, we couldn't reach 911MHz HD 2600 XT clock on HD 2600 Pro card.
We haven't had much luck with the Samsung memory, 860MHz for the Pro and 874MHz for the XT card. We found that Jetway's Web site states that the memory is 1.2ns which means that it should work at 800MHz, but the memory on the cards is 1.1ns which should give the 900Mhz clock; but it was simply unreachable. It is probably limited by the PCB design. As we already said, the GDDR3 memory is clocked at 700/1400 with 128bit memory interface.
The cooler did a good job and the noise stayed at acceptable levels. We measured a maximum temperature of 67 °C for XT and 65 °C for the Pro version. Of course, we are talking about the temperatures of overclocked cards, while the reference clocks gave 57 °C under load and 46 °C in idle mode.