Definitions for "Front Side Bus"
Keywords:  fsb, agp, pci, mhz, bus
Processor speed is a product of two numbers, the bus speed (also called Front Side Bus, or FSB), and the multiplier. The FSB speed is the speed at which the processor talks to the rest of the computer, and is by default 66MHz for almost all processors up to 333MHz, and 100MHz for 350MHz and faster processors. Many motherboards support other FSB speeds - 75, 83, 112 and 133MHz, for example - but non-standard FSB speeds usually entail non-standard PCI bus speeds, since the PCI bus speed is set as a fraction of the FSB speed and is only likely to be the correct 33MHz when you're using an "official" FSB speed. Old motherboards set PCI speed as half of FSB, which makes FSB speeds above 75MHz very tricky. Clock your PCI devices too fast and they may work. Or they may not. The multiplier is the ratio between the processor's speed of operation and the FSB speed. A 66MHz FSB and a 4.5X multiplier gives you a 300MHz processor. So does a 100MHz FSB and a 3X multiplier, but the faster FSB in the second case will make the computer perform (very slightly) better.
The speed of the bus connecting the microprocessor, its chipset, and connected main memory. In architectures where the processor interacts directly with...
The connecting path between the processor and other key components such as the memory controller hub. FSB speed is measured in GHz or MHz.