Serious Sam, Unreal Tournament 2003
Serious Sam: SE
Vendor: Croteam - (Website)API: DirectX 8.0
Pixel Shader Version Supported: No pixel shaders

The X800 PRO has some resource usage issues in SS:SE, limiting its performance somewhat, resulting in identical performance to the 9800 XT, as if one of the X800 PRO's quad pipelines had been turned off. No such problems with the 6800 Ultra in this old school test.
Unreal Tournament 2003
Vendor: Epic - (Website)API: DX8.0
Pixel Shader Version Supported: PS1.1, some limited PS1.4 shaders to render terrain in less passes

The X800 PRO and 6800 Ultra trade blows in this test, with it too close to call a real-world winner, despite the 6800 Ultra holding 8.5% more speed over the X800 PRO at the upper setting. Both hold serious margins over the 9800 XT, itself a card that doesn't find UT2003 too hard to render at speed.