Anti-Aliasing and Anisotropic Filtering


Here we'll run through the Anisotropic and FSAA levels available on the X1000 series of boards to see what what kinds of performance hits there are for the levels of each available. This test uses the same Doom 3 timedemo used earlier in this article, at 1600x1200 with the Ultra settings enabled.

Anisotropic Filtering Performance

  1x  2x  4x  8x  16x 
X1900 XTX  118.3  115.2  115.4  114.3  114.5 
X1800 XT  103.5  101.5  101.5  100.4  98.6 

fps

Anisotropic Filtering Performance Differences

  1x  2x  4x  8x  16x 
X1900 XTX to X1800 XT  14.3%  13.5%  13.7%  13.8%  16.1% 
X1900 XTX diff from 1x    -2.6%  -2.5%  -3.4%  -3.2% 
X1800 XTX diff from 1x    -1.9%  -1.9%  -3.0%  -4.7% 

percentage

In this instance we can see that despite more texture layers theoretically minimising the differences between the X1900 and X1800, because the test should become more texture limited, reducing the overall importance of the shaders, we see that the performance gap between the X1900 and X1800 actually increases with more texture layers, as opposed to decreases. However, this is a fairly small difference and given the performances of these boards aren't really swayed significantly by these Anisotropic Filtering changes it could just be a margin of error.

FSAA Performance

  Normal  2x  4x  6x 
X1900 XTX  118.3  104.5  84.5  65.9 
X1800 XT  103.5  93.2  73.4  57.3 

fps

FSAA Performance Differences

  Normal  2x  4x  6x 
X1900 XTX to X1800 XT  14.3%  12.1%  15.1%  15.0% 
X1900 XTX diff from 1x    -11.7%  -28.6%  -44.3% 
X1800 XTX diff from 1x    -10.0%  -29.1%  -44.6% 

percentage

The performances of the different levels of FSAA show that, although this is quite a bandwidth bound operation, the X1900 XTX is able to maintain, or even slightly increase, its performance lead over the X1800 XT with higher levels of FSAA.

FSAA and 16xAF Performance

  Normal  2x  4x  6x 
X1900 XTX  114.5  98.1  82.0  63.5 
X1800 XT  98.6  89.3  70.7  55.6 

fps

FSAA and 16xAF Performance Differences

  Normal  2x  4x  6x 
X1900 XTX to X1800 XT  16.1%  9.9%  16.0%  14.2% 
X1900 XTX diff from 1x    -14.3%  -28.4%  -44.5% 
X1800 XTX diff from 1x    -9.4%  -28.3%  -43.6% 

percentage

With both FSAA and 16x AF combined, although the performance differences between the X1900 XTX and X1800 XT are a little variable, on balance the X1900 does lose out a little of its advantage to the X1800 at higher levels of AA.