Teh reson why there so overclockable. becuase the core.. The first amd 64 2800+ that I have, its 130um core. uses 1.4 Voltage sounds big? Everytime the core number gets smaller = more Cache mosty, and save more power. The less core = Better overclock Example:
AMD 64 2800+ ( 130um Core = 1.5V ). The motherborad is overclockable and the cpu voltage goes to 1.7V, well that .30V to play with.
AMD 64 3000+ ( 90um Core = 1.2V ). The motherborad is overclockable and the cpu voltage goes up to 1.7, This .50V to play with..
The lower the Core size = Better overclock with stock voltage and more room to up the voltage