Benchmark Results: Audio/Video Encoding
Utilizing the same processor yields similar results in iTunes. The slight lead for the stock March PC is likely due to higher RAM data rate, while a higher HyperTransport link speed could explain the narrow victory the June PC pulls once overclocked.
The $550 PC trails by a few seconds and finishes two minutes and 21 seconds quicker when overclocked. HandBrake is well-threaded, so the overclocked quad-core CPU makes the others look slow.
The trend continues as the June PC trails a few seconds back at stock speeds. DivX benefits from the extra core, while Xvid rankings closely mimic the results at stock speeds.
Nearly identical encoding times for the two stock systems are reduced by 30 seconds from overclocking alone. However, unlocking an extra core yields even better gains.