Simply put, the x264 HD Benchmark is a reproducible measure of how fast your machine can encode a short HD-quality video clip into a high quality x264 video file. It’s nice because everyone running it will use the same video clip and software. The video encoder (x264.exe) reports a fairly accurate internal benchmark (in frames per second) for each pass of the video encode and it also uses multi-core processors very efficiently. All these factors make this an ideal benchmark to compare different processors and systems to each other. We are using x264 HD v5.0.1 for this test.
This application did fairly well when run on 8 threads, as you can see from the screen shot above. The first pass was not using all of the processing power available on the cores, but on the second pass all 12 threads were at ~95% load.