i am curious about the clock speed of every processor

i know the processor speed is determined by the processor multiplier times the system front side bus.

but my question here is, how is the multiplier of the processor be set? is it set internally in the processor die, or set by the capacitor and resistor value on the processor ( like the old version of amd athlon, where the pencil trick work). what is different inside the processor core of a 2.0GHz P4 and a 3.0GHz P4 of the same architecture, same FSB, same socket design?