Overclock Testing and Performance

In any video card review, the question of overclocking potential is an important one, as any extra juice you scan squeeze from it represents cash back in your pocket. Although ATI video cards are not as well known for their overclocking as the long-running NVIDIA coolbits hack, high-end models like the Radeon X1900 XT 512MB do have the Overdrive feature enabled through the ATI drivers. Sure, there are other applications that can overclock ATI cards, but due to their reliance on certain Catalyst revisions and the quick release schedule of ATI drivers, we prefer this method, assuming we don't hit the upper limits of the program.

Our first step was to unlock the driver utility and let Overdrive automatically determine optimal clock speeds through its configuration utility. Our findings using this technique have been very good, and the ATI drivers regularly hit the maximum overclock, or extremely close to it. This tends to push the video card extremely hard, and it's not a rare occurrence to have the drivers temporarily lock or crash the card while trying to find the optimum speed. In this case, we reached 662 MHz core and 1.57 GHz memory speeds, and although we could move the memory slider up a notch to approximately 1.58 GHz, the core refused to budge. Another great job by the ATI Overdrive utility and a very nice overclock that exceeded the ATI Radeon X1900 XTX clock speeds.

To see exactly how these overclock speeds impacted performance, we ran several of the most popular game benchmarks (Chronicles of Riddick, DOOM 3, FarCry, Quake 4, and F.E.A.R.), at 1600x1200 using both standard details and 4X AA/8X AF settings. These scores are then compared to the previous results using the Radeon X1900 XT 512MB at default clock speeds. The charts are presented in a "% increase" format and these illustrate how the overclocked speeds influence gaming performance.

Our first chart demonstrates how the 662 MHz core and 1.58 GHz memory overclock affected standard 3D gaming at 1600x1200. There was a noticeable improvement in the majority of game tests, and we see F.E.A.R. pushing over 9% and Chronicles of Riddick not far behind at more than 8%. The only abstainer is FarCry, and it has historically been a game that doesn't react well to most clock speed increases, at least using standard detail settings.

The second chart increases the detail settings to 4X AA and 8X AF, while maintaining the 662 MHz core and 1.58 GHz clock speeds. This extra workload translated into gains in FarCry, but surprisingly, there is very little improvement in the other benchmarks. Some do jump, but only by small percentages, as in less than 1%.

* Please keep in mind that these overclocking results are based on the review card, and as such, should not be used a blanket statement concerning all Radeon X1900 XT 512MB cards. In hardware overclocking, just like with many things in life, your mileage may vary.