Overclocking The Radeon X850 XT PE
When we first looked at ATi's Radeon X800 Pro and X800 XT back in May of this year, we found that the X800 XT Platinum Edition had very little headroom left for overclocking the core. Its default clock speed was 520MHz, and we were only able to crank things up by a meager 14MHz. With that in mind, we didn't expect the X850 XT Platinum Edition to do much better, but we were wrong...
Our particular Radeon X850 XT Platinum Edition proved to be quite the overclocker. Using the built-in auto-overclocking options available to X850 owners in the latest driver release, we were able to reach a maximum stable core clock speed of 594MHz, a full 54MHz (10%) increase. We were also able to overclock the memory a bit, reaching 1.24GHz from a default speed of 1.18GHz. At these speeds, the Radeon X850 XT Platinum Edition was completely stable, and we saw no visual artifacts whatsoever. In fact, we were able to hit higher clock speeds for both the core and memory, and our test system remained stable, but we did see some visual anomalies.
With the card overclocked, we re-ran the high-resolution Aquamark 3 and Doom 3 benchmarks, with 4X antialiasing and 8X anisotropic filtering enabled. In the Aquamark 3 test, the overclocked X850 gained about 3.5 frames per second, an increase of 7.1%. Performance in Doom 3 also went up, increasing by almost 9%.