The final speed of any CPU is given by a multiplier located in the CPU that times the bus.
i.e. Duron 1100 MHz= 10 (multiplier) x 100 MHz (system bus)
As you see, if the multiplier and/or the bus change, the speed of the CPU changes.
Normally the bus is able to be changed however, the multiplier is locked in all recent Intel and AMD CPUs.
With AMD CPUs there are a couple of tricks to unlock the multiplier, so you would be able to raise the bus and drop the multiplier i.e. 133 MHz bus x 8.5 multiplier= 1130 MHz.
Finally, I would <font color=red>not recommend</font color=red> you to do any work around multiplier unlocking until you have enough knowledge about it.
<b>(<font color=yellow>as good as it looks</font color=yellow>)</b>