Front Side Bus (FSB)

  FSB is also known as the Processor Bus, Memory Bus, or System Bus and connects the CPU (chipset) with the main memory and L2 cache. 

The FSB can range from speeds of 66 MHz, 133 MHz, 100 MHz, 266 MHz, 400 MHz, and up. The FSB is now another important consideration when looking at purchasing a computer Motherboard or a new computer.

            The FSB communicates with components through the computer’s chipset. The chipset consists of two processors, known as the Northbridge and the Southbridge. These two chips collect data from specific components, channeling all information to the CPU through the front side bus.

                          The speed of the front side bus is measured in Megahertz or Gigahertz, just like the processor. Most computers' processors run faster than their system buses, so the FSB speed is typically a ratio of the processor speed. For Example :- a Pentium 4 processor that runs at 2.4 GHz may have an FSB speed of only 400 MHz . The CPU to FSB ratio would be 6:1. A Power Mac G5, however, with a 2.0 GHz processor, has a 1.0 GHz front side bus. 
 Therefore, its CPU to FSB ratio is 2:1.


                                                                  Back Side Bus :-