A Matter Of IQ
In addition to the raw performance of a card, image quality is becoming more of a deciding factor for the prospective buyer. Edge smoothing, or FSAA (full scene anti-aliasing), and texture filtering through anisotropic filtering tremendously improve the visual quality of games. Since these features are also the biggest performance killers, both ATi and NVIDIA are investing a lot of effort into developing optimizations that achieve a good balance between quality and performance.
The ATi Direct3D.
Using "tricks" to improve performance is most common in anisotropic filtering, to such an extent that one could argue the feature no longer deserves the name. ATi even calls it "adaptive anisotropic filtering," meaning not all textures are filtered at the level set in the driver. Instead, the driver or the chip determines the level of filtering needed based on the position and distance of a texture. This setting is controlled through the options "performance" and "quality" in the driver menu.
Obviously, the best results are achieved when both features are used in combination. The Radeon 9500/ 9600/ 9700/ 9800 family offers a full 36 different combinations: standard mode, three FSAA modes, and eight anisotropic modes (quality/ performance), for a total of 24 FSAA/ anisotropic settings alone! If that seems like a lot to you, take a look at NVIDIA's GeForce FX 5600/ 5800: standard, 42 FSAA modes (balanced, quality, performance, plus a "texture sharpening" setting for each), and nine levels of anisotropic filtering. That makes for a grand total of 378 individual FSAA/ anisotropic combinations and 429 possibilities overall!!!
For comparsion: NVIDIA's 3D quality settings.
Good luck keeping all of those straight! We decided to limit our tests to "quality" mode using the most important (comparable) modes (2x/ 4x FSAA, 8x anisotropic filtering and 4x FSAA + 8x anisotropic) so we would have enough time to bring you more than just a list of benchmark results.