Overclocking
We’ll take a look at the overclocking capabilities of the reference sample of the 6600 GT AGP. As usual, bear in mind that the overclocking is indicative only of the sample that we have in our position and may or may not translate into similar levels on retail boards – especially so given this is a reference sample and board vendors may alter their board designs from the reference, which can also alter the properties of the board and the levels they can potentially reach.
The initial overclocking levels were gained from NVIDIA’s “Detect Optimal Frequencies†speed test in the “Clock Frequency Settings†control driver panel available by Coolbits. Coolbits initially set a speed of 563MHz for the core and 508MHz (1016MHz effective) for the RAM, however this resulted in artefacts appearing in Far Cry with FSAA and AF enabled, so the speeds were dialled back a little to 555/500, which resulted in a stable overclock in these tests. These increases represent an 11% theoretical performance increase in terms of both core speed and bandwidth.
| Far Cry (FPS) | 640x480 | 800x600 | 1024x768 | 1280x1024 | 1600x1200 |
| Default (500/450) | 93.1 | 93.0 | 85.4 | 62.9 | 46.3 |
| 555/500 | 92.9 | 93.0 | 89.8 | 70.5 | 51.4 |
| % Increase | -0.2% | 0.0% | 5.2% | 12.2% | 11.0% |
| Far Cry, 4x FSAA + 8x AF (FPS) | 640x480 | 800x600 | 1024x768 | 1280x1024 | 1600x1200 |
| Default (500/450) | 86.5 | 69.2 | 49.3 | 32.7 | 19.2 |
| 555/500 | 90.3 | 76.6 | 54.5 | 36.0 | 21.6 |
| % Increase | 4.3% | 10.7% | 10.6% | 10.2% | 12.7% |
| Doom3 (FPS) | 640x480 | 800x600 | 1024x768 | 1280x1024 | 1600x1200 |
| Default (500/450) | 126.7 | 118.3 | 91.6 | 63.7 | 46.9 |
| 555/500 | 127.1 | 121.7 | 100.5 | 70.4 | 52.1 |
| % Increase | 0.3% | 2.9% | 9.7% | 10.5% | 11.1% |
| Doom3, 4x FSAA + 8x AF (FPS) | 640x480 | 800x600 | 1024x768 | 1280x1024 | 1600x1200 |
| Default (500/450) | 89.0 | 65.6 | 46.4 | 31.2 | 17.8 |
| 555/500 | 98.1 | 72.7 | 51.5 | 34.9 | 19.1 |
| % Increase | 10.2% | 10.8% | 11.0% | 11.9% | 7.3% |
In its overclocked state the 6600 GT AGP board is offering performances inline with the theoretical performance increases where the performance is solely reliant on the core speed or memory bandwidths. There isn't a full gain at 1600x1200 on Doom 3 with FSAA and AF enabled since the performance is bottlenecked by the system bus as texture data is addressed across it.
