X-bit labs

S3 Chrome S27 Graphics Processor Review: Worthy Performance for Its Class? (page 9)

Category: Video

by Alexey Stepin , Anton Shilov

[ 12/29/2005 | 12:11 PM ]

Vertex Shader Performance

The 4 vertex processors of the Chrome 27 clocked at 700MHz deliver the same or higher performance than the 3 such processors of the GeForce 6600 clocked at 300MHz only. We begin to suspect the driver again, or rather their incompatibility with 3DMark2001 SE, and that’s why:

It is quite different from the 3DMark2001 SE standings: the Chrome S27 is only second to the RADEON X700 which has 6 vertex processors on board.

This test performs transform and lighting functions over several highly-polygonal models. The total number of vertices is about 6 millions and this is a real burden on the GPU’s vertex processors. The Chrome S27 is fantastically fast in this test, outperforming the RADEON X700 that has more vertex processors. This is probably because the test just requires nothing else but high speed of simple vertex shaders. This is what the Chrome S27 can do, especially with that high core frequency of it!

The Complex Vertex Shader test is much more sophisticated as it uses vertex shaders to render some vegetation, each grass-blade being processed independently. The S3 Chrome S27 seems to have some caching-related problems as its performance degenerates more than the other cards’ as the resolution grows. On the other hand, even in 1600x1200 it is only slower than the RADEON X700 – quite an achievement considering that the latter has as many as six vertex processors.