Half-Life 2 Performance Benchmark Preview

By now you've heard that our Half-Life 2 benchmarking time took place at an ATI event called "Shader Day." The point of Shader Day was to educate the press about shaders, their importance and give a little insight into how ATI's R3x0 architecture is optimized for the type of shader performance necessary for DirectX 9 applications. Granted, there's a huge marketing push from ATI, despite efforts to tone down the usual marketing that is present at these sorts of events.

One of the presenters at Shader Day was Gabe Newell of Valve, and it was in Gabe's presentation that the information we published here yesterday. According to Gabe, during the development of Half-Life 2, the development team encountered some very unusual performance numbers. Taken directly from Gabe's slide in the presentation, here's the performance they saw initially:

Taken from Valve Presentation

As you can guess, the folks at Valve were quite shocked. With NVIDIA's fastest offering unable to outperform a Radeon 9600 Pro (the Pro suffix was omitted from Gabe's chart), something was wrong, given that in any other game, the GeForce FX 5900 Ultra would be much closer to the Radeon 9800 Pro in performance.

Working closely with NVIDIA (according to Gabe), Valve ended up developing a special codepath for NVIDIA's NV3x architecture that made some tradeoffs in order to improve performance on NVIDIA's FX cards. The tradeoffs, as explained by Gabe, were mainly in using 16-bit precision instead of 32-bit precision for certain floats and defaulting to Pixel Shader 1.4 (DX8.1) shaders instead of newer Pixel Shader 2.0 (DX9) shaders in certain cases. Valve refers to this new NV3x code path as a "mixed mode" of operation, as it is a mixture of full precision (32-bit) and partial precision (16-bit) floats as well as pixel shader 2.0 and 1.4 shader code. There's clearly a visual tradeoff made here, which we will get to shortly, but the tradeoff was necessary in order to improve performance.

The resulting performance that the Valve team saw was as follows:

Taken from Valve Presentation

We had to recap the issues here for those who haven't been keeping up with the situation as it unfolded over the past 24 hours, but now that you've seen what Valve has shown us, it's time to dig a bit deeper and answer some very important questions (and of course, get to our own benchmarks under Half-Life 2).