To overclock the Gigabyte Radeon HD 7770 OC video card we used AMD Overdrive to find the highest stable overclock without any voltage increases.
The AMD Radeon HD 7770 reference card comes clocked at 1000MHz on the core and 1125MHz on the memory. If you use CATALYST Control Center (CCC) like we did, you can raise or lower the clock frequencies within the parameters set by AMD. For this card AMD set limits for this particular BIOS to 1200MHz on the core and 1250MHz on the memory. Gigabyte has this card overclocked up to 1100MHz on the core and 1250MHz on the memory, so they increased the headroom available for overclocking. AMD OverDrive allowed us to overclock this card up to 1320MHz core and 1500MHz memory.
We were able to run the card at 1060MHz on the core and 1300MHz on the
memory without any stability issues. If we bumped up the core clock frequency any higher it would cause the game or benchmark to hard lock and we had to
kill the application in task manager. The memory was also having issues over 1300MHz, so we locked it in there and dealt with it. Here is a GPU-Z screenshot showing the overclock! This is a 60MHz overclock on the core and 50MHz on the GDDR5 memory. This is a mild 5.45% overclock on the core, so don’t expect any miracle performance increases in performance.
Gigabyte Radeon HD 7770 OC at 1000MHz core and 1250MHz memory:
Gigabyte Radeon HD 7770 OC at 1060MHz core and 1300MHz memory:
We tried out this overclock with Futuremark 3DMark 11 on the performance preset and saw the score go from P3828 to P3993, which is a 4.3% or 165 3DMark point increase from the card’s stock settings. This is the third AMD Radeon HD 7770 video card that we have overclocked and we have yet to get one past 1175MHz, so this card is just 15% shy of the best that we have seen. It appears that the factory overclock is pretty decent and not too much headroom is left in these cards.