yeah, most modern computesr are based around a crystal that puts out
exactly 14.something MHz
. that signal is sent to the "PLL", which multiplies/divides it as necessary to give you all the different frequencies in the system (like 8mhz for ISA, 33 for PCI, 100 for fsb, 133 for ram, 48 (?) for usb, etc)
some components have their own crystals. my NIC has a 20mhz crystal, and a video card i have here has a 25mhz crystal. an alpha ev4 daughtercard here has a 250mhz crystal