Now, let’s estimate how big gets the performance drop when NVIDIA GeForce FX performs full-screen anti-aliasing.

Unreal Tournament 2003 comes first. The settings are the same: Texture Detail: Highest, World Detail: Highest, Character Detail: Highest, Physics Detail: Normal, Character Shadows: ON, Dynamic Lighting: ON, Detail Textures: ON, Projectors: ON, Decals: ON, Coronas: ON, Decal Stay: Normal, Foliage: ON, Trilinear Filtering: ON. We ran the Antalus flyby-scene.

We used “Speed” and “Quality” settings for ATI RADEON 9700 PRO in Direct3D as well as in OpenGL. The settings are those as shown in the above driver screenshots with one exception: we turned off anisotropic filtering and activated different full-screen anti-aliasing modes.

NVIDIA GeForce FX and ATI RADEON 9700 PRO with enabled full-screen anti-aliasing do not lose too much of their performance compared to NVIDIA GeForce4. The support of frame-buffer compression comes in handy here.

The lower memory bus bandwidth of GeForce FX accounts for its bigger performance drop in the highest-quality and slowest “Application” mode. In “Balanced” and “Aggressive” modes in 800x600 and 1024x768 resolutions, the CPU becomes the bottleneck of the system and even 2x FSAA doesn’t lead to any considerable performance reduction.

The workload of the graphics cards is higher in 1280x1024, but still NVIDIA GeForce FX does well. It all becomes clear in 1600x1200: the graphics memory bus bandwidth is the bottleneck here and ATI RADEON 9700 PRO shows a lower performance drop.

The graphics memory bus bandwidth is the crucial factor in 4x full-screen anti-aliasing, too. GeForce FX in the “Application” mode still loses to ATI RADEON 9700 PRO. “Balanced” and “Aggressive” modes reduce the amount of texturing data transferred through the graphics memory bus and GeForce FX shows smaller performance drop than RADEON 9700 PRO in lower resolutions. But in 1280x1024 and 1600x1200 this no longer helps: the lower memory bandwidth drags GeForce FX down.

Only NVIDIA graphics chips participated in this test: ATI RADEON 9700 PRO doesn’t support the combination of supersampling and multisampling.

Thanks to frame-buffer compression support, NVIDIA GeForce FX 5800 Ultra suffers a lower performance decrease compared to GeForce4. But this reduction is still higher than in case of 4x FSAA, because of supersampling used.

Actually, this comparison is not quite correct, although both cards use six samples for calculating one pixel color. ATI RADEON 9700 PRO uses “pure” multisampling, while NVIDIA GeForce FX 5800 Ultra – a combination of supersampling and multisampling.

The results speak for themselves: the “pure” multisampling is faster :).

There is nothing to comment on: NVIDIA GeForce FX could only run in up to 1280x1024 resolutions in the 8xS mode and also suffered a colossal performance drop: 70%-80%.

Quake3 Arena uses OpenGL. This means 4xS, 6xS and 8xS modes are not available here for NVIDIA GeForce FX and GeForce4.

We used the following game settings: 32-bit textures and frame-buffer color depths, maximum amount of textures and objects, enabled tri-linear filtering, disabled textures compression.

NVIDIA GeForce FX manages 2x FSAA in Quke3 Arena very well. Thanks to frame-buffer compression, GeForce FX is much better than GeForce4 here. Considering ATI RADEON 9700 PRO suffers significant performance drops, the graphics memory bus doesn’t become a bottleneck for GeForce FX in Quake3 Arena any more.

However, there is one more explanation of good results shown by GeForce FX in this game: without anti-aliasing the performance of GeForce FX is normally greatly limited by the CPU performance. Now that full-screen anti-aliasing is enabled, the system loses less fps due to the CPU’s limiting effect.

The lower graphics memory bus bandwidth of GeForce FX shows itself in the 4x mode. This GPU suffers a bigger performance drop than ATI RADEON 9700 PRO.

Summing it all up, we can put forth a few observations.

First, 6xS and 8xS modes, although they are good at smoothing polygons with nearly vertical edges, are hardly better than 4x on nearly horizontal edges. Considering the high performance tradeoff and their availability in Direct3D only, we don’t think they will be used often or at all. Anyway, the new FSAA modes of GeForce FX don’t bring any advantage over the anti-aliasing implemented by ATI.

The good old 2x and 4x of NVIDIA GeForce FX provide the same quality of “jaggies” smoothing as 2x and 4x of ATI RADEON 9700 PRO, but the advantage of the rotated grid from ATI is clearly seen at edges angled closer to absolute horizontals and verticals.

2x and 4x methods result in a lower performance drop in NVIDIA GeForce FX compared to GeForce4 Ti4800 thanks to its frame-buffer and Z-buffer compression. Moreover, NVIDIA GeForce FX with its 128-bit memory bus looks worthy even against ATI RADEON 9700 PRO with its 256-bit memory bus at 2x and 4x FSAA. Only in the highest resolutions in 4x mode, GeForce FX suffers a greater performance loss than RADEON 9700 PRO due to its lower graphics memory bus bandwidth.