X-bit labs

ATI RADEON X800: R420 Totally Exposed (page 29)

Category: Video

by Tim Tscheblockov , Alexey Stepin , Anton Shilov

[ 05/04/2004 | 06:42 AM ]

We used an updated version of our Xbitmark test package to test the graphics cards in a bit bigger set of shaders:

The results of Xbitmark are very interesting. On the one hand, RADEON X800 XT outperformed GeForce 6800 Ultra in most shaders, but there are a few shaders where RADEON X800 XT falls pretty far behind its rival.

If we compare the results obtained by ATI RADEON X800 XT and NVIDIA GeForce 6800 Ultra in different shaders, we will discover an interesting tendency: RADEON X800 XT looks worst of all in shaders using a lot of textures, and best of all in shaders rich in mathematical calculations.

The worst shaders for RADEON X800 XT are “8 textures” and “NPR”, which also uses a lot of textures. And the most advantageous shaders are “Wood” and Factored BRDF+HDR”, i.e. the shaders rich in calculations. The picture is pretty familiar, don’t you think so? We have already faced the textures sampling problems by RADEON X800 XT in the very first test, when we checked the texturing speed with Fillrate Tester.

So, according to the results obtained in Xbitmark, we can conclude that texturing samples in the shaders are a weak spot of the new RADEON X800, while mathematical calculations, on the contrary, are a strength of the new ATI architecture.

NVIDIA GeForce 6800 Ultra copes perfectly well with the textures in shaders, but is less efficient than RADEON X800 for shaders rich in mathematical calculations.

These tendencies can be easily observed in “Dot Product Bump Mapping”, “Dot Product Bump Mapping+Specular” and “Dot Product Bump Mapping+Specular+Reflection” shaders. The more calculations are involved, the more at home RADEON X800 XT/PRO feels and the slower GeForce 6800 Ultra gets.