How to overclock a amd radeon hd 7770

Solution
Go to CCC control panel under performance, AMD Overdrive. Click enable graphics overdrive.

Then move the sliders to the desired overclock. Note this will raise temps and you may need to increase fan speed.
also how well cooled is your Sapphire 7770? I have the same card but not the OC edition, the highest clock rates I've gotten my card to is 1250MHz on the memory clock and 1150MHz on the gpu clock with it being stable. I have a Zalman CPU fan and that fan alone has not only helped my CPU stay cool but keeps my GPU cool as well.