I know on my machine I can only half the Mem speed on Afterburner, so I have to down clock it from 1200 to 600, restart Afterburner then I can go from 600 to 300.
i see the same thing...I have to down clock it from 1200 to 600, restart Afterburner then I can go from 600 to 300, but there are any risk to down clock so hard?
I downclock all the way to 150 on my 6950's, but all they do is mine. On my main machine I downclock to 300 on my 5870's and haven't seen any problems as long as I don't watch videos or play 3D games. It's pretty stable for normal use.