(FSB) The bus via which a processor communicates with its RAM and chipset one half of the Dual Independent Bus, the other half being the {backside bus}. The {L2 cache} is usually on the FSB, unless it is on the same chip as the processor [example?]. In PCI systems, the PCI bus runs at half the FSB speed. Intel' s Pentium 60 processor used a bus speed and processor speed of 60 MHz. All later processors have used multipliers to increase the internal clock speed while maintaining the same external clock speed, e.g. the {Pentium 90} used a 1.5x multiplier. Modern {Socket 370} motherboards support multipliers from 4.5x to 8.0x, and FSB speeds from 50 MHz to a proposed 83 MHz standard. These higher speeds may cause problems with some PCI hardware. Altering the FSB speed and the multiplier ratio are the two main ways of overclocking processors. {Toms Hardware - The Bus Speed Guide (http://www.tomshardware.com/busspeed.html)}. {Toms Hardware - The Overclocking Guide (http://www.tomshardware.com/overclock.html)}. (2002-02-21)