PC Architecture. A book by Michael B. Karbo

Copyright Michael Karbo and ELI Aps., Denmark, Europe.
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Chapter 18. Overclocking
The Pentium II was subjected to a lot of overclocking. It was found that many of Intel’s CPU’s could be
clocked at a higher factor than they were designed for.
If you had a 233 MHz Pentium II, you could set up the motherboard to, for example, run at 4.5 x 66 MHz,
so that the processor ran at 300 MHz. I tried it myself for a while, it worked well. At a factor of 5 it didn’t
work, but at factor of 4.5 it functioned superbly.
CPU
System bus Clock
factor
Internal clock
frequency
Pentium 66 MHz 1.5 100 MHz
Pentium MMX 66 MHz 2.5 166 MHz
Pentium II 66 MHz 4.5 300 MHz
Pentium II 100 MHz 6 600 MHz
Celeron 100 MHz 8 800 MHz
Pentium III 133 MHz 9 1200 MHz
AthlonXP 133 MHz x 2 13 1733 MHz
AthlonXP+ 166 MHz x 2 13 2167 MHz
Pentium 4 100 MHz x 4 22 2200 MHz
Pentium 4 133 MHz x 4 23 3066 MHz
Pentium 4 200 MHz x 4 18 3600 MHz
Figur 122. The CPU’s internal clock frequency is locked to the system bus frequency.