Front Side Bus (FSB)

Front-Side Bus (FSB) is an interface between microprocessor core and other computer components, such as memory, peripheral devices and other microprocessors. FSB is often called a "system bus". Microprocessor performance highly depends on the speed, width and latency of the system bus:

• Wider system bus allows the CPU to transfer more data during each bus cycle.
• Faster system bus allows the CPU to transfer data faster from/to memory or peripheral devices.

Please note that buses of many modern microprocessors utilize dual-data and quad-data rate transfers, which effectively doubles and quadruples bus speed. For instance, the bus of first Pentium 4 microprocessors was clocked at 100 MHz. Because the data could be sent 4 times during each bus cycle, the bus effectively worked as 400 MHz bus.