Performance in FSAA Modes
Besides comparing the quality of the different FSAA modes supported by the GeForce 8800, we also compared their influence on the speed of the card in the popular 3D shooter Half-Life 2: Episode One that runs on the advanced Source engine. The results are listed below:
It’s clear that the simpler 2x and 4x FSAA modes are virtually free on such a powerful solution as the GeForce 8800 GTX, as opposed to the ex-flagship GeForce 7950 GX2. The latter suffers a performance hit in high resolutions in spite of its total of 48 TMUs and 32 ROPs.
It’s more interesting with the high-quality antialiasing modes. The 8xS mode is useless even in 1600x1200 whereas the only mode where the performance of the GeForce 8800 GTX declines with the growth of the resolution is CSAA 16xQ. The results of the card in 8x CSAA, 8xQ MSAA and 16x CSAA modes are identical. It means you can use either of them in Half-Life 2: Episode One, but the 8xQ MSAA mode is going to be the optimal choice if you want to have the highest antialiasing quality without losing in speed. As we’ve found out already, this mode is the most optimal in terms of “hit accuracy” and the precision the color of the final pixel is calculated at.
The CSAA 16xQ mode can also be used in practice, but it is heavy even for the GeForce 8800 GTX in the resolution of 1920x1200 pixels. Nvidia didn’t implement 16x MSAA and quite rightly because this would provide a negligible quality improvement over 16xQ CSAA while the performance hit would be too big for practical purposes.
After discussing FSAA and anisotropic filtering issues we can now proceed to theoretical tests.