How Does a Computer Motherboard Work?

By Billy Kirk


A motherboard serves a critical purpose in a computer. It is the workhorse behind the computer's processes, helping to link everything together and run the computer. The motherboard links together many processors and parts to ensure everything works efficiently.

Motherboard's Purpose

A motherboard houses all the main elements of the computer. The first element that comes to mind is the CPU, which is an integral component in determining the speed of a computer. Located on the motherboard, the CPU must be matched with a compatible motherboard so that it may fit into the motherboard's sockets. The CPU uses the chipset of the motherboard to communicate with other devices.

Northbridge and Southbridge

The chipset located on the motherboard that is utilized by the CPU consists of chips that are housed in two separate areas. It's a permanent fixture and cannot be replaced. The Northbridge talks to and helps manage the CPU, RAM and many video processes, while the opposite side, the Southbridge, communicates with the other devices. The devices the Northbridge and Southbridge communicate with largely depend on those devices' location within the computer; the Northbridge handles one side and the Southbridge the other. Either way, the Northbridge and the Southbridge manage what goes on within the computer and act as an aid in the communication between multiple devices and chips. The motherboard has to understand all of the separate processes, interpret what one device is asking of another, and facilitate that request by more or less connecting the two devices together. Specifically, the Northbridge is connected to the processor from the front side bus. It also can connect to the PCI Express bus and to the memory. In fact, a memory controller that provides the CPU with the ability to jack into the memory is also found on the Northbridge. The Southbridge, meanwhile, has to wait on communications from the CPU to go through the Northbridge first, so communication in this region is certainly slower.


Also integral to the makeup of the motherboard are the buses, which connect areas of the motherboard to other areas of the motherboard. Each bus has a speed rated in MHz that determines how quickly the information can travel. This speed is measured by the front side bus, which, as mentioned, facilitates connecting the Northbridge to the CPU. Other specific buses are the memory bus, backside bus and PCI bus. The motherboard has a hand in the processes of all of these devices.