Motherboard Components

Before you start

Objectives: learn the different components which can be found on typical Motherboard.

Prerequisites: you should be familiar with ports which can be found on typical computer.

Key terms: motherboard, connector, cpu, port, power, expansion, memory, slot, card, bios, chipset

Example Motherboard

In our example we will work with Asus A8N SLI Motherboard.

 Asus A8N Motherboard

Image 227.1 – Example Motherboard

Let’s take a look at every important component which all typical Motherboards have.

CPU Socket

On every Motherboard we will have some kind of CPU socket, which has to be compatible with the CPU. On the picture below we can see the fan and the heat sink.


Image 227.2 – CPU Fan

CPU is mounted below the fan and the heat sink, in our case, into socket 939.

Socket 939

Image 227.3 – CPU Socket

Pins in the processor drop into the processor socket. The motherboard socket must match the socket type and design used by the processor. When choosing a motherboard we have to make sure it matches the processor which we will use. Some motherboards support multiple processors and will have a socket for each processor.


On the picture below we can see memory slots. These are the slots into which we install system memory, often referred to as RAM.


Image 227.4 – RAM Slots

Different Motherboards contain slots for different types of memory. Memory modules must be compatible with the type supported by the the processor and by the chipset on the Motherboard.

Expansion Slots

We can also have a series of expansion slots which are used for inserting expansion boards that allow us to add new features to our computer.

Expansion Slots

Image 227.5 – Expansion Slots

There are number of different standards of expansion slots, including Industry Standard Architecture (ISA), Peripheral Component Interconnect (PCI) or Accelerated Graphics Port (AGP).

IDE and Floppy

We can also have a connector that we use to connect our Floppy Disk Drive. In our case we also have two connectors that we can use to connect IDE devices to our Motherboard.

IDE Connectors

Image 227.6 – IDE Connectors

6 Floppy

Image 228.7 – Floppy Connector


In addition to IDE ports, this particular Motherboard has Serial ATA interfaces as well.


Image 227.8 – SATA Connectors


Most newer motherboards additionally have USB built into the motherboard itself. In our case we have three different USB connectors.


Image 227.9 – USB Connectors

These are used to connect USB devices such as the front panel USB connector or USB connectors that are installed in an empty expansion slot in the back. These are included in addition to the built in USB connectors that are connected back on the Faceplate.


We also have BIOS and CMOS chip. The BIOS chip is firmware (hardware hard-coded with software) attached to the Motherboard and is essential in booting the computer.


Image 227.10 – BIOS

On older systems these were two separate chips. On a modern system such as this they’re all combined into a single chip.


We also have our battery that powers our CMOS to make sure we don’t lose our settings that we configure.


Image 227.11 – Battery


In addition to BIOS we also have Chipset. The Chipset is a group of chips that facilitate communication between the processor, memory components, and peripheral devices. The Chipset controls the bus speed and also power management features. Chipsets are usually attached to the motherboard and are non-upgradeable. Most modern chipsets consist of the following:

  • Northbridge chip provides control for main and cache memory, the front side bus, and the AGP and PCIe graphics. The Northbridge is closest to the CPU. The Northbridge dictates the CPU and memory type supported by the motherboard. On some motherboards, the Northbridge chip includes an integrated graphic processor. The northbridge often has a heat sink and sometimes a fan, especially if it includes built-in video.
  • Southbridge chip provides the real time clock, controls power management, and provides the controllers for the PCI bus and USB devices.
  • There are two other important chipsets on a motherboard: the keyboard controller and the I/O controller.

On older systems, Northbridge and Southbridge were usually implemented as two separate chips. On a newer system however we might find both the North Bridge and the South Bridge incorporated into a single chip, as in our case.


Image 227.12 – Chipset

On this Motherboard, that single chip is beneath this fan, since it can get really. Recent developments for the chipset include moving the memory controller from the Northbridge to the CPU itself to improve memory access by the CPU.


Newer Motherboards, because of the CPU requirements, also have an additional power connector, beside the regular power connector. But many will only need the regular power connector.

 Power Connector

Image 227.13 – Power Connector

Additional Power Connector

Image 227.14 – Additional Power Connector

When we’re buying a Motherboard and mating it up with a case and Power Supply, we need to make sure that we chose the correct combination. If our Motherboard requires this extra four pin connector, then we need to make sure that the Power Supply we purchase has that same four pin connector. Otherwise the system might not work.


Older Motherboards used to use a lot of jumpers in order to configure various parameters of the board. Jumpers are electrical connection points that can be set to control devices and functions attached to the Motherboard. Some functions controlled by jumpers are clearing the CMOS password, clearing the CMOS settings, setting the CPU bus speed, and enabling or disabling onboard components. Today we don’t see that many jumpers on motherboards because most of the configuration is handled through the CMOS setup program. However there are still a few around.


Every connector on our Motherboard should have a label right next to it. That provides us with a good clue as to what the particular slot is, so we can use that label to look up in the documentation and find out the specifics.

Other Features

Some motherboards will also have CD Audio connector. What we do with that is connect that connector with a cable up to our CD or DVD drive. This allows us to play audio CDs in our drive, and have the signal for the sound to come down to the Motherboard and be processed and handled by our audio board.

Many Motherboards include onboard devices such as network cards, audio cards, video cards. Selecting a Motherboard with onboard devices is typically cheaper than buying separate expansion cards for each feature. However, the quality of onboard devices might not be as high as the quality we could get from devices through expansion cards.


On the back of our Motherboard we can have different ports and connectors available. A Faceplate fits over the Motherboard’s ports to secure them and protect the Motherboard from dust and debris. Some standard connectors for onboard I/O components don’t require expansion cards. These connectors typically include the following: PS/2 mouse and keyboard ports, USB ports, Serial ports (COM 1, 2, 3, and 4), Parallel ports (LPT 1 and 2), Mic in, line in, line out connectors, and MIDI/Game port.


Image 227.15 – Faceplate

So, for different motherboards we will typically have to use different faceplates. In most cases, faceplates come with the motherboard itself. In our case we have the mouse and keyboard connectors.

Mouse and Keyboard

Image 227.16 – Mouse and Keyboard Ports

We also have a Parallel port.


Image 227.17 – Parallel Port

We have coaxial SPDIF out port.

Coaxial SPDIF Out Port

Image 227.18 – Coaxial SPDIF Port

We have optical SPDIF out port.

Optical SPDIF

Image 227.19 – Optical SPDIF Port

We have Ethernet LAN port.

Network Interface

Image 227.20 – RJ45 Port

We have IEEE 1294a port.


Image 227.21 – Firewire Port

We have USB ports.

USB Ports

Image 227.22 – USB Ports

And finally we have Audio connectors.


Image 227.23 – Audio Connectors


When installing the motherboard into the computer case, the first thing is to make sure that we have standoffs (also called riser screws( properly aligned in the computer case. Standoffs have to be aligned with the holes on our motherboard.

1 standoff


Standoffs are to be screwed into the available holes in the computer case. Standoffs make sure that there is space between the computer case and the motherboard, for the purpose of air flow and short circuit prevention. Motherboard will lie on the standoffs. Then we can put the screws in that will hold the motherboard to the computer case. Screws will go into the standoffs.

After that we can connect all of the available connectors to the motherboard. Keys on the connectors will prevent us from pluging them the wrong way. For power and reset buttons, power LED, speaker, front USB, etc, we should check documentation to make sure that we connect those wires correctly.


When working with Motherboards, a good place for information is the Motherboard documentation. Most Motherboard documentation includes a diagram that identifies the components listed above and details any jumper settings. If you are missing the motherboard documentation, check the manufacturer’s Web site.