When I overclock my VRAM from 1150MHz (standard) to 1200MHz via AMD's overclock feature, I'm unable to reset back to 1150MHz. I surely can hit "reset", but the clock doesn't go down anymore. Also the idle state doesn't work for VRAM anymore. It is settled @ 1200MHz all the time. Even a reboot did not solve the problem. I tried to reinstall the whole driver + software. It worked, but when I overclock again, the same problem persists. Also I can't set the VRAM clock manually back. The software thinks 1200MHz is the lowest clock.
I'm using the newest Crimson 16.1 and a HD7770
Is a known issue, being looked into.
Use cards oc utility or afterburner for the time being.