Gigabyte doesn't offer any specific tools to overclock the GV-RX18L256V-B, so we downloaded and installed the latest version of ATiTool. For a free piece of software, this is a great tool for finding out everything you need to know about your graphic card. Switching over to the overclocking screen, we can change the core and memory speeds, while simultaneously checking for artifacts. There are also options to automatically find the Max speeds, but we wanted that fun for ourselves. We moved the sliders for each clock speed a few MHz at a time until we ran into a few system lockups or driver crashes. After some further tweaking, we arrived at a completely artifact-free environment. The final results were a Core clock speed of 577 MHz, and we pushed the memory to 621MHz (1242MHz effective). To see what kinds of gains these higher speeds afforded us, we re-ran two of our benchmarks and compared the new results to the original scores.
By raising the core and memory speeds, we were able to get above the X850XT's speeds. In doing so, we've increased our 3DMark05 score by 8%, and Doom 3 by almost 20%. It's a nice jump in performance, especially when it's essentially accomplished for free. Unfortunately, as evidenced by the Doom 3 results, it still might not be enough to overcome the 7800GT in many of our tests.