you do realize that for bitcoin mining, you're supposed to downclock memory A LOT, right? not sure how it is with 7000 series but I can downclock my 5850 from 1000 to 300 with hash rate increase!
Yes, I've under-clocked my memory from 1500Mhz to 110Mhz. The problem is that this doesn't allow me to further OC my core clock, nor does it decrease power usage or temperatures.
EDIT: Update on my temps. After letting it run for a few hours, my temps are about 92C/78C Not sure what I can do to reduce these. I might have to resort to water cooling.