Overclocking

XFX included an overclocking utility on their drivers CD, which turned out to be a registry key that opens up the overclocking section on nVIDIA’s control panel. Overclocking the card is pretty easy – you can have the drivers select the optimal settings by running a test, or you can select the settings yourself by adjusting sliders for the GPU core clock and the memory clock. There’s also a test button so the system can confirm that your selection won’t lock up the card and by default, the system only keeps the configuration active until you restart, which is good if you mess something up.

The test button didn’t always behave as it should (i.e., run the optimal settings test first then adjust slowly from there), but in the end I managed to push the GPU core clock up to 602 MHz and the memory clock to 887 MHz, a nice gain over the stock 480 MHz (GPU) and 700 MHz (memory) found on standard 7900 GS cards. That said though, the default speeds on the 7900 GS ExTreme are 525 MHz (GPU) and 775 MHz (memory), so you’re basically paying XFX to get a guaranteed speed boost that you might or might not get if you went with the standard 7900 GS.

I did note that using the video card overclocking option that ASUS included in their motherboard BIOS actually lowered the maximum number of MHz I could pull out of the card by about 30 MHz, so you might want to disable any performance gain in your BIOS to get a few more clock cycles out of the card through the nVIDIA control panel.

After overclocking the card, I ran 3DMark 06 again and came up with these results:

3DMark Score: 7,066
SM2.0 Score: 3,226
HDR/SM3.0 Score: 3,312
CPU Score: 1,600

Besides the average 2.68% gain achieved by overclocking the video cards, what’s also interesting about these results is that it puts the system in the top seven percent of all 450,000 plus systems surveyed by Futuremark – not bad for two “value” cards, especially when you consider that many of those top systems are SLI rigs themselves.