X-bit labs

The Fast and Furious: ATI Radeon X1900 XTX Review (page 12)

Category: Video

by Anton Shilov , Alexey Stepin

[ 01/24/2006 | 08:28 PM ]

Vertex Shader Performance

As in case of pixel shaders 1.1, vertex shader 1.1 test shows that performance is limited by something else than vertex shader performance of the modern VPUs.

Approximately 660 thousand triangles are skinned in each frame using vertex shaders 1.1. As we see, there is virtually no scaling across resolutions, which means that the test is actually limited by vertex shader performance, or, at least, something else related to vertex shaders. Generally, the Radeon X1900 XT is ahead here, even though the gap could be larger keeping in mind the 100MHz clock-speed difference between the newbie and the GeForce 7800 GTX 512.

Short and simple vertex shaders 2.0 are performed pretty well by all high-eng graphics cards today, but the Radeon X1900 XTX seems to be notably ahead of the competition due to high clock-speeds.

The same vertex shader 2.0 from the 3DMark06 benchmark, however, performs notably better on the Nvidia GeForce 7800 GTX 512 hardware and slight better on the Radeon X1800 XT GPU. We do not know the reason for that, as Futuremark claims in its documents (1, 2) that these shaders are identical. Moreover, it is unclear which result is correct for Nvidia GPU.

There is no difference between 3DMark05 and 3DMark06 for the case of the complex vertex shader 2.0:

The gap between the Radeon X1900 XTX and the GeForce 7800 GTX 512 has shrunk significantly compared to the previous case in the 3DMark05, even though the former still maintains lead. The reason for that may be the central processing unit that calculates fractal noise for this test scene, even though Futuremark believes that CPU impact here is negligible.