I currently have my agression set to 13. For me there is no tradeoff actually since the machine is only used through ssh, nfs and as a router. There is never any monitor connected to it. I have tried increasing the agression, decreasing it, but it does not really change the GPU load.

I already did install the 11.6 driver, at least, I assume the 'ati-driver-installer-11-6-x86.x86_64.run' file is Catalyst 11.6. I still do not see any option to change the clock any further. I'd love to get more out of these cards, as they're now humming away at about 73 degrees (celsius) I think they could go a good bit higher.