Not only is it 100 MHz, you should not try adjusting it to Overclock a NON K CPU. Some do, ie raise it ro 103 MHz., But:
.. It's not worth it, in that 3 MHz x multiplier of 33 only eauals 100 Mhz, or a increase CPU of 3% - never notice it.
.. This is also used for PCI-e bus which is NOT very friendly to changes in the 100 MHz.