Overclocking the cards properly mean we need to look elsewhere for software and although ATI supply Overdrive within the driver it does not allow us to crank the card to the maximum speeds we can achieve. We used the combination of MSI Afterburner and AMD GPU Clock tool which means we can enhance both clock speeds and increase the fan speeds of the card.
We got great overclocks with the Powercolor card and while it didn’t quite reach the same levels as the Sapphire, they are still very impressive. We achieved a 140mhz overclock on the core and a 150mhz overclock on the memory giving an effective 4800mhz. The temperatures of the card rose by 9c under load which is still less than the reference card at default clock speeds.
As we mentioned earlier we wanted to try S.T.A.L.K.E.R. Call Of Pripyat again once we worked out the maximum overclocked speeds. We had issues getting a smooth gameplay experience at the pre-overclocked speeds, but after we cranked the cards to the redline we can see that HD5870 speeds are in our grasp. The game went from being a little juddery to perfectly smooth. Sure, temperatures rise a little but for this kind of improvement its worth it.