Serious Sam - Second Encounter (SS:SE)
Here we'll uses the OpenGL renderer of SS:SE.

640x480 | 800x600 | 1024x768 | 1280x1024 | 1600x1200 | |
Normal | 67.0 | 74.4 | 56.2 | 37.0 | 26.4 |
3X FSAA | 28.6 | 36.3 | 26.0 | 17.3 | 4.1 |
% Diff | -57% | -51% | -54% | -53% | -84% |
In the lower resolutions we can see that this title is quite CPU limited, but soon becomes fill-rate limited at 1024x768 and beyond. As we saw with RtCW, although not quite as pronounced, the rendering performance at 640x480 is lower than at 800x600, to quite a significant degree in this instance.
The performance impact for enabling 3X FSAA is in the 50%-60% region, except at 1600x1200 where we have the performance drop off, as evidenced by all the OpenGL titles.
Whilst altering the settings for SS:SE benchmarking I noticed the following in relation to the Xabre board:
The screenshot above shows that, despite a 32-Bit frame-buffer output being selectable, the Xabre drivers have limited the texture quality to only 16-Bit under OpenGL, which will, no doubt, have some impact on performance of all the OpenGL based benchmarks we've look at so far. SS:SE does have both an OpenGL and DirectX renderer and this behaviour was evident only under OpenGL, presumably because these drivers are WHQL certified and MS has some checks for this on the DirectX side.

640x480 | 800x600 | 1024x768 | 1280x1024 | 1600x1200 | |
P4 2.53GHz | 67.0 | 74.4 | 56.2 | 37.0 | 26.4 |
P4 1.8GHz | 55.5 | 56.7 | 48.5 | 34.0 | 24.3 |
% Diff | -17% | -24% | -14% | -8% | -8% |
As expected, we can see that there is a performance difference between the two CPU's, however these converge as the board is getting more fill-rate limited at higher resolutions.
640x480 | 800x600 | 1024x768 | 1280x1024 | 1600x1200 | |
AGP4X | 66.7 | 73.4 | 54.1 | 36.6 | 25.7 |
AGP8X | 67.0 | 74.4 | 56.2 | 37.0 | 26.4 |
% Diff | 0.4% | 1.4% | 3.9% | 1.1% | 2.7% |
Again, we can see that the AGP8X bus is offering a very slight advantage over the 4X bus. It's a little odd that the performance difference is greater at higher resolution, where there should be less onus on the system bus.