Audio
Lame and OGG appear to gain nothing from the extra cores of the mid-priced Q6600 and high-end QX6850 systems, reflecting an almost perfect scale of clock speed to encoding time among the three systems.
Video
DivX 6.6 loves quad cores, giving the mid-priced and high-performance systems a significant boost in encoding time. Conversely, XviD has no preference for the added cores and instead reflects the clock speed difference proportionately.
Applications
3D Studio Max loves it when we increase clock speed or add more processing cores, so it's not surprise that combining these traits makes the overclocked high-performance system a superstar.