Vertex Shader Performance

Assuming that NVIDIA didn’t bring any serious improvements into the architecture of the vertex processors but just increased their number, the results are not surprising at all: the 6 processors of the RADEON X850 XT Platinum Edition work at 540MHz whereas the 8 vertex processors of the GeForce 7800 GTX are clocked at 430MHz.

It’s different in the analogous test from 3DMark03: the GeForce 7800 GTX is about 15% faster than the RADEON X850 XT Platinum Edition and 30% faster than the older GeForce.

The Simple Vertex Shader test performs transformation and lighting of six multi-polygonal models, each of which consists of 1 million vertexes. There is only one light source in the scene. The load on the vertex processors is high, but the vertex shaders employed are very simple; they could have been fitted into Shader Model 1, that’s why the test is called Simple. Here, the RADEON X850 XT Platinum Edition enjoys a certain advantage over the new best product from NVIDIA. The reason is the same ?higher core frequency.

The Complex Vertex Shader test is ?as its name suggests ?much more complex. Vertex shaders are used here to create an infinite sea of grass, each blade being processed independently. The outcome is, however, similar to the previous test: the GeForce 7800 GTX is slower than the RADEON X850 XT Platinum Edition despite having more vertex processors.

The vertex processor test from mark resembles the Simple Vertex Shader test from 3DMark05, so the results are similar, too.

Thus, the new graphics card from NVIDIA is not as good at processing geometry as it is at executing pixel shaders. However, it is not much worse than the RADEON X850 XT Platinum Edition, so we don’t expect the performance of the GeForce 7800 GTX to degenerate much in games with complex geometry.