Overclocking

Here we'll take a look at the overclocked performance of the GeForce 7800 GTX. Bear in mind that the overclocked speeds are not representative of all boards of its kind, especially so as this is a reference board, however gains similar to these may be available elsewhere. The board tested here was able to overclock the core from its default speed of 430MHz to 509MHz, representing an 18% performance increase, whilst the memory moved from 600MHz to 650MHz, representing an 8% increase in memory bandwidth.

Half Life 2 (FPS) 640x480 800x600 1024x768 1280x960 1600x1200
Default (430/600) 113.5 112.7 112.2 109.8 86.8
509/650 112.6 112.1 111.7 111.1 97.5
% Increase -0.8% -0.5% -0.5% 1.2% 12.4%

Half Life 2, 4x FSAA & 8x AF (FPS) 640x480 800x600 1024x768 1280x960 1600x1200
Default (430/600) 112.5 112.3 105.8 90.1 61.0
509/650 112.5 112.2 109.9 100.1 70.4
% Increase 0.0% 0.0% 3.9% 11.1% 15.3%

Doom3: Resurrection of Evil (FPS) 640x480 800x600 1024x768 1280x1024 1600x1200
Default (430/600) 60.6 60.4 60.2 59.8 58.2
509/650 61.0 60.7 60.7 60.4 59.5
% Increase 0.7% 0.5% 0.8% 1.0% 2.2%

Doom3: Resurrection of Evil, 4x FSAA & 8x AF (FPS) 640x480 800x600 1024x768 1280x1024 1600x1200
Default (430/600) 60.1 59.3 57.0 47.0 36.7
509/650 60.6 60.1 58.4 51.9 41.1
% Increase 0.8% 1.3% 2.5% 10.4% 12.0%

Obviously the largest performance gains are on the situations where processing is most graphics bound, which isn’t the case at lower resolutions, or in our Doom 3: Resurrection of Evil test under normal rendering at high resolution, as these cases are largely CPU bound. However, under Normal rendering at high resolution Half Life 2 gains 12%, which is probably largely due to the increased shader rate from the core overclock. With FSAA and AF enabled the gains for Half Life 2 are even greater at high resolution, more than the memory overclock increase suggesting that the level is quite texture bound with these settings. With FSAA and AF enabled the performance increase for the Doom 3: Resurrection of Evil test is also greater than the memory overclock, suggesting that this too gets a little texture bound with 8x AF enabled.