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Computer Motherboard Tutorial

Computer Motherboard   This tutorial discusses the various motherboard components and features. For information on installing a motherboard, read this tutorial.

The motherboard (mobo for short) is the most important part of a computer and is the main circuit board. Everything connects directly or indirectly to it.

To become familiar with motherboards, you need to know and understand their parts. PC motherboard components differ depending on the manufacturer and model. However, all have the following primary features:
  • BIOS Chip
  • Battery
  • Form Factor
  • Type of Processor They Support
  • Chipset
  • Type of Bus & Bus Speed
  • Expansion Slots
  • Memory Slots
BIOS Chip:
Every motherboard has a BIOS (Basic Input Output System). This chip contains a small amount of code that is responsible for booting up your system. It reads the CMOS settings, performs the POST (Power On Self Test), checks for devices, and then reads the master boot record on the hard drive so the operating system can load. Phoenix Technologies and American Megatrends are the two main BIOS makers.

Every motherboard has a battery to maintain the time and CMOS settings after the power is turned off. Most are small, round, flat and fit into a socket.

CMOS Battery

Form Factor:
The form factor refers to a motherboard's dimensions and layout of its components. The primary standard today is some type of ATX form factor, developed from the obsolete AT. ATX and micro ATX (mATX) are still the most popular, but there are others such as Extended ATX(EATX, which is slightly bigger than the standard ATX) and mini ATX (smaller than ATX but bigger than mATX). VIA developed the mini ITX factor, which is smaller than any of the aforementioned.

Small motherboards were basically designed for low cost PCs but still implement the latest technology. A main disadvantage, though, is they have fewer expansion slots than their larger counterparts.

Form FactorSize
ATX (Standard)9.6" x 12"
microATX9.6" x 9.6"
Extended ATX13" x 12"
Mini ATX8.2" x 11.2"
Mini ITX6.7" x 6.7"

Type Of Processor Support:
Every motherboard supports either an AMD or an Intel processor (called the central processing unit or CPU). They are not interchangeable. If a motherboard requires an AMD processor, it cannot use an Intel, and vice-versa. You don't have to figure out which CPU matches a particular board. You're always told the type of CPU that a motherboard uses.

The chipset is either one chip or a pair of chips that allows communication between the CPU and other components. If there are two chips one is called the northbridge and the other southbridge.

The northbridge connects directly to the processor through the front side bus and lets it talk to the memory, AGP, and PCI Express controllers. The southbridge connects to the processor indirectly via the northbridge and controls slower devices such as the hard drive, USB, audio, video, LAN, and PCI. If there is one chip, then everything is controlled by that chip.

Northbridge and Southbridge

The motherboard is useless without a chipset. Unlike the CPU, it is integrated into the motherboard, so it can't be removed. When a new processor is developed, a new chipset has to also be developed to accommodate its technology. The two main manufacturers are nVIDIA and Intel.

Bus & Bus Speed:
In electronics, you can think of a bus as an electronic highway on which data travels. With computers there has to be a communication highway between the CPU and other parts. AMD motherboards use HyperTransport technology for data transport and Intel's Core i7 processor-based systems use QuickPath Interconnect. But before these there was/is the front side bus.

On current Intel computers not using the Core i7 processor, the front-side bus is still used as the data path that connects the processor to the northbridge and other components. When shopping for a computer or a motherboard you're almost certain to see the speed listed as something like "1333 MHz". This is the front side bus speed, also known as the motherboard speed. It is how fast data travels between the CPU and memory and is measured in megahertz (MHz). This speed is obtained by using a quartz crystal on the motherboard. When an electrical current passes through it, it vibrates. These vibrations, or pulses, occur millions of times per second. This is what's known as the clock speed.

HyperTransport and QuickPath Interconnect measure speed in GT/s (Giga transfers/sec) and sometimes MT/s (Mega transfers/sec). This is not the actual bus speed but how many transfers, or operations per second. Data is sent on the rising and falling edges of a clock cycle, resulting in two transfers per cycle. So if the bus speed is 1500 MHz (1.5 GHz) that means there are 1500 million rising and falling edges every second. Multiply that by 2, and you get 3000MT/s (3.2 GT/s). HyperTransport and QuickPath are explained in a little more detail on the CPU page. Bus speed is one of the primary factors that has an impact on a computer's performance.

Although front side bus technology no longer exists on any current AMD motherboards, some retailers still use the term to describe HyperTransport.

Motherboard expansion slotsExpansion Slots:
All computers now-a-days come with audio, video, and other features built right into the motherboard. If you don't want to use these, expansion slots give you the flexibility to choose and have your own audio, video, or other card installed. The number of slots varies according to the manufacturer and model. The board on the left has 2 PCI slots (white) and 2 PCI Express Slots (Black).

Understanding PC motherboard components can greatly help you, but choosing one is still sometimes a confusing ordeal. After all, there are so many manufacturers. But one main thing to remember is that since motherboards support either an Intel or AMD CPU, picking a motherboard and processor go hand in hand, so think about which processor you want first. However, this in itself opens another can of worms because there's an on-going debate about which CPU is better. It seems to never end. And each CPU manufacturer produces various models to add to the confusion. The best thing to do is read reviews of different motherboards and the latest processors. Some main motherboard manufacturers are:
How to install a motherboard

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