We performed our overclocking directly from ATI’s Overdrive tool; we didn’t meddle with voltages. ATI Overdrive allows for overclocking the GPU up to 1GHz, which is a pretty tough feat to perform on most HD 5870s without meddling with GPU voltages. Our Club3D HD 5870 OC Edition card performed pretty well with 940MHz for the GPU, and our hat is off to Club3D as the card took all this in stride and still remained silent.



Club3D used a non-reference fan which performs its job admirably. We initially performed our overclocking with the fan set at maximum RPM, but the fan got pretty loud. After we reached stable 940MHz for the GPU we lowered the RPM and have seen that the card will run stable with the fan at 60% RPM. This resulted in 82°C GPU temperatures and almost inaudible cooling.



The following table shows a few different setups and temperatures we measured after stressing the GPU with FurMark build 1.8 test.

FAN RPM 100% (OC)	GPU Temp 72°
FAN RPM 90% (OC)	GPU Temp 74°
FAN RPM 80% (OC)	GPU Temp 76°
FAN RPM 70% (OC)	GPU Temp 78°
FAN RPM 60% (OC)	GPU Temp 72°
FAN RPM 100% (OC)	GPU Temp 82°
FAN RPM 50% (OC)	Failure
FAN AUTO RPM (OC)	GPU Temp 77°
FAN AUTO RPM (NO OC) - Load	GPU Temp 74°
FAN AUTO RPM (NO OC) - Idle	GPU Temp 35°

As you can see for yourself, the cooler does its job with no trouble whatsoever. Maximum GPU temperatures without overclocking amounted to 74°C, which is 12°C less than on the reference HD 5870. Idle mode shows temperatures identical to the reference cooling and both coolers ran very quiet in this case.

Overclocking brought only 5% better results in FarCry2 with consumption increasing by the same amount.