There using that Overdrive. I do it by the bios. Since it unlocked you can use either the X or the bus. Or alittle of both. Depends, you can just use the X and bump up the CPU voltage to get as high as you can, and everything else stays at default setting (memory and HT). If you use the Bus the memory and HT gets overclocked, then you have to start looking at your N/B and memory voltage.
When they are talking about overclocking the N/B they are refering to the Hypertransport, it can be done by the Bus if your using it to overclock the CPU or by the HT X in the bios.