Simply put, this test measures how fast your machine can encode a short, DVD quality MPEG-2 video clip into a high-quality x264 video clip. What's x264, you ask? It's more or less the next-generation Xvid/DivX codec. I think it's ideal for a benchmark because the application (x264.exe) reports fairly accurate compression results (in frames per second) for each pass of the video encoding process, and it uses multi-core processors very efficiently.
x264 HD gives results for 2 passes when compressing an MPEG-2 clip into x264. It presents 4 separate results for each pass giving a total of 8 - all results are given in FPS. For each pass I have averaged out the results.
The D3 does an admirable job in the 1st pass but drops in the 2nd pass at stock speeds. Ultimately, overclocking ensures the very peak of performance.