Clock Multiplier Table
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This table contains the driving clock speeds and the clock multipliers for AMD/Cyrix/Intel processors
brandCPU name-
rated speed
internal speed
[Mhz]
multiplierclock (mem bus)
[Mhz]
PCI bus
[Mhz]
Notes/P-rating
Intel/AMD/Cyrix 486 Class 486DX2-66662x3333
486DX2-80802x4040??
Cx486DX4-75753x25?
486DX4-1001003x3333
AMD Enhanced 486 Class 486DX4-1201203x4040??
486DX4-1201002x50?2x mode (non-standard)
Intel Pentium® Pentium®-75751.5x5025
Pentium®-90901.5x6030
Pentium®-1001001.5x6633
Pentium®-1201202x6030
Pentium®-1331332x6633
Pentium®-1501502.5x6030
Pentium®-1661662.5x6633
Pentium®-2002003x6633
AMD 5x86 Amd5x86-1331334x3333P75+
Amd5x86-133160**4x4040*?P100+(non-standard)
Amd5x86-133150**3x5050*?n/a (non-standard)
Cyrix 5x86 Cx5x86-1001002x/3x50/33P75+
Cx5x86-1201203x40P90+
Cyrix 6x86 Cx6x86-1001002x5025*P120+
Cx6x86-1101102x55?P133+
Cx6x86-1201202x6030*P150+
Cx6x86-1331332x6633*P166+
Cx6x86-1501502x7540*P200+
NexGen Nx586-80?I couldn't find any info on this processor
Notes * are my speculations.
** are overclocked modes. (may damage the CPU, see Overclocking FAQ).
Cyrix 486DX4, 5x86 and 6x86 have 2x/3x clock multiplier.
Amd 5x86 has 3x/4x clock multiplier.
PCI specs are for 33Mhz; dunno if or how PCI stands overclocking to 40 or 50 Mhz.
Only Intel Pentium®s and Cyrix 6x86 have triple clocks (internal/memory/PCI bus). For the others the PCI clock is the same as the memory clock, if not forced to 33 Mhz.

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