Frontside Bus

What Does Frontside Bus Mean?

A frontside bus is a communication interface that serves as the main link between the CPU and system memory and other parts of the chipset and motherboard. It was actively used in computer architecture in the 1990s-early 2000s, and because the speed of this communication link could be a bottleneck in computer systems, it was considered an important measure of computer performance.


The FSB connects the following components with the CPU:

  • System chipset
  • System memory
  • Graphics card through the northbridge
  • Other input/output devices
  • PCI cards

Techopedia Explains Frontside Bus

The FSB was a prominent computer architecture component that allowed a CPU to communicate with various computer system resources. It connected the system memory, input/output (I/O) peripherals and other board components to the CPU and acted as the main transport link for data around the computer hardware. However, although the FSB was a very important component, its limited speed also made it a major bottleneck.

FSB speed is measured in hertz (Hz) and is often also expressed as a ratio to CPU speed. For example, a processor running at 2.4 GHz with an FSB of 400 MHz would have a CPU to FSB ratio of 6:1.


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Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.