Make sure that you have catalyst a.i. turned on in Catalyst Control Center. The x2 I was working was playable at up to 1680x1050 with medium-high settings, it however isn't as good as it should be since crossfire scaling in that game is horrendous.

I've tried playing with a number of settings in the CCC (Catalyst Control Center), as well as attempting to update to the latest driver from ATI. I don't recall the driver version offhand, as I'm currently not at the same computer. What I did find is that the card seems to want to run underclocked on the GPUs. I haven't found any setting (yet) that corrects this. Perhaps one of the next driver releases in the near future may handle this better. I think the drivers are supposed to be smart enough to scale GPU speed based on demands for energy efficiency, but its not working right with the current drivers.

In the meantime, what I am using as a patch solution is using RivaTuner (freeware, google it) which provides the ability to tweak fan and GPU speeds manually and tell it to apply the settings on windows startup. I went from being unstable in 3D games at 297 MHz, to rock solid at 825 Mhz. Also, I kicked up the default fan speeds on the cards just as a preference (40% fan speed), though not really necessary. There's some handy RivaTuner setup guides out there, if you need them.

If I was at my home PC, I would probably have some direct links to offer you. And if anyone has any better suggestions for handling this, I'd also be interested in hearing them.