PowerColor's HD 7870 showed some serious overclocking prowess with a significant boost in core clock speed with a smaller boost in the overall memory clock speed. By using MSI's Afterburner utility I was able to boost the clock speed on the core by 255MHz over the baseline non-boosted clock speed of 925MHz. That in itself is a 27%+ boost in clock speed without the ability to tweak the voltage outside of adjusting the power limit. The memory overclocking was a bit subdued with a 112MHz bump over the factory 1500MHz or just over 7%. In each and every benchmark the clock speed increases offered up significant FPS or scoring improvements that add performance for your dollar. To ensure stability I did increase the fan speed to 100% to keep the GPU as cool as it could be under load. With just the single fan and smallish heat sink the temperatures were higher than I was expecting but still low enough to stabilize the overclocks.



Link: OCC