Overclocking

Overclocking does not seem to work with these cards. ATITool 0.26 and before will not work at all since the RV570 chip is not supported in these versions. ATITool 0.27 Beta "Driver Level Overclocking" can overclock one GPU, but not the second, because it can't access it even though it appears to the system as just another PCI-E device. Changing only one card's clock does not yield any benefits since the faster (overclocked) GPU has to wait for the slower GPU to finish its work each frame.

ATI's WinCLK sees both adapters and lets you change clocks, but even with the slightest change in clocks the cards crash almost instantly during benchmarks.

My educated guess is that these limitations are not caused by the board design but by the state of the overclocking software. It may be possible to achieve overclocking by editing the BIOS of both cards for higher clocks, but I did not try that because another editor is waiting for me to ship the card to him and he would not appreciate a broken card in case something goes wrong...