Introduction: Computer processors can be overclocked by changing two different settings. One of these is the "bus frequency" which runs at 66MHz for Celeron processors, and 100MHz for Pentium III processors (neglecting 133MHz for now).  Going above these values for either processor is called "bus overclocking".  

  The second setting that can theoretically be changed to affect processor speed is called the "multiplier".  All processors run faster than the bus frequency, because they can perform multiple operations per clock cycle. So a 500MHz Pentium III is rated as such because it has a 5X multiplier on a 100MHz bus. Changing a multiplier setting to a higher value than set by the manufacturer is called "multiplier overclocking". 

  Processor manufacturers have been putting so-called "multiplier locks" on all of their processors for several years now, which prevent using any multiplier other than the factory default. This was not done so much to prevent overclocking, as it was to prevent illegal  "remarking" of chips. 

  Intel instituted multiplier locks on their Pentium II line of chips in 1998. Since that time, you could only overclock newer Intel processors by pairing them with a motherboard which allowed the user to adjust the frequency of the bus clock generator.  Intel's Pentium III processors are renowned for their conservative rating, and ability to be overclocked by upping the bus frequency.  The Pentium III 450 often could be run at a bus setting of between 124MHz and 130MHz, yielding total speed ratings of between 558MHz and 585MHz. 

  Bus frequency overclocking has two consequences not found with multiplier overclocking.  These are the fact that bus overclocking increases the speed of all the different parts of the motherboard, thus speeding up all the other components in your computer.  This is good for improving performance, but it leads to the second consequence.  At some point, as you continue to increase the bus speed, either your memory, video card, or one of your PCI cards is not going to be able to handle the speed increase, and the computer will hang. 

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