I have a 6850, slight stock OC (800/1050). I am having an issue getting memory clocks below 1000. I am using for GPGPU, that is totally uneffected by memory speed, and lowering lowers my temp by ~6C. I was able to get it to work before, sometimes, and once by force killing CCC. I restarted today to install a 6570, and now it is back to not going below CCC limit of 1000, even if CCC is uninstalled. Using MSI Afterurner.