Chapter 4 - Understanding Motherboards

2023-03-16 1247 words 6 mins read

Chapter 4 - Understanding Motherboards.

This article is Chapter 4 in the CompTIA A+ certification course on that teaches you an Understanding of Computer Motherboards.

Understanding Motherboards


• Function of motherboards

  • A house for everything needed to make a computer operate.
  • Contains CPU, RAM memory slots, Cache memory, Chip sets, BIOS/CMOS battery, Expansion slots, Serial/parallel slots, Connectors for mouse & keyboard, sound & video cards, and Fans.
  • All necessary in computer to turn inputs to outputs.
  • Form factors are used to describe the dimensions and layout of the motherboard components.
  • Motherboards are not interchangeable.
  • Most common: Advanced Technology Extended (ATX) Motherboard

Location of Primary Components & Motherboard Chipsets

Read the diagram from the top going clockwise:

Motherboard Chipsets.
  1. CPU - Central Processing Unit
  2. AGP - Advanced Graphics Port
  3. PCIe - Peripheral Component Interconnect Express - Interface for connecting Perephrial Devices
  4. IDE - Integrated Drive Electronics - Used for storage devices
  5. PCI - Peripheral Component Interconnect - Provides a bus for attaching devices to computers
  6. USB - Universal Serial Bus - Allows for connections for input and output devices.

North Bridge

  • The North Bridge is located close to the CPU.
  • Responsible for communication from CPU to Memory.
  • Second largest chip after the Processor.
  • Usually has a fan or heat sink above it.

South Bridge

  • The South Bridge is located farther from the CPU by the PCI slots.
  • Responsible for communication between the CPU and other devices such as the IDE, PCI, and other devices.
  • Located farther from the CPU, next to PCI slots.

Front and Side Panels

Front and Side Panels.

In primary areas, you will connect input and output devices to.

• Audio connections

  • Audio port connections such as headphones.

• Drive activity light

  • Lets you know whether the system is busy, indicated by a light flashing when the system is reading.

• Power light

  • Power on the light and button that lets you know the system is running.

• On/off button

  • Lets you turn the system on or off and even perform cold boot if necessary

• USB connections

  • Common for universal serial bus connections

Many connections on computers are based on the manufacture of computers and their applicational purpose.

• Power cord

  • Supplies power to the motherboard which then supplies power to components on the motherboard.
  • Motherboard uses different drives and power connectors like ATX power connectors which come in 3V, 5V, or 12V.

• PCIe connectors

  • 6-pin connectors
  • Connect things like Graphics and GPU.

• SATA connectors

  • which connects external drives through a USB port.
  • Different versions you can use.
  • Hot-swappable technology (Can remove drivers while the system is running).

Cache Memory

Cache Memory.

In short, cache memory is used to speed things up.

• Cache memory

  • Stores the most frequently accessed data, and makes data access fast for subsequent requests.

• Level I

  • All processors have an integrated cache memory known as Level I
  • Is built into the processor.
  • Not integrated cache, built on the outside of the processor on the motherboard.

• Level II

  • Independant memory for the processor core.

• Level III

  • Shared cache between each processor core.

RAM Slots

It’s important for the A+ exam to be familiar with the types of sockets, and be able to know how to install the memory.

RAM Slots.

• RAM slots

  • Provide memory for your computer

• Memory slots and sockets

  • Used to add additional memory and functionality to the computer.
  • Each provides different benefits to the computer or user.


  • Dual Inline Memory Module
  • Used to install memory
  • Manufacturers use a number of these sockets on the motherboard which are usually blue, black, or white.
  • Can be installed individually or via the dual channel.
  • Dual channel architecture increases performance with the ability to send and receive two 64-bit chunks as opposed to the typical one 64-bit chunk.
  • Can be used to speed up and increase capacity.

BIOS Chips

BIOS Chip.

• Basic input/output system BIOS-Chips

  • Allow devices to communicate with each other on the motherboard.
  • Read-only memory chip, you can’t write data to this chip.
  • You can use an Erasable Programable Rom Chip (EPC Rom Chip), available from the manufacturer, and this allows you to update the BIOS if you wanted it to support a larger disk. So it can be rewritten to.
  • Primary function of this chip is to control the boot process for the power on self-test.
  • This test allows the PC to check out the systems to ensure they are OK.
  • After it gives the OK, it locates the bootable partition from the master boot record, which loads the operating system.



  • Random Access Memory
  • The computer’s primary working memory
  • Temporary in nature


  • Read Only Memory
  • Used to store BIOS
  • Used to store power on self-test
  • EPROM and the newer EEPROM have software on a chip that can be upgraded using special software from the manufacturer.
  • Popular way to update BIOS and hardware as it improves.

Expansion Slots

Expansion Slots.

Do exactly what they sound like.

• Expansion Slots

  • Allow the motherboard to expand in functionality by adding additional cards in the expansion slot.
  • Use PCI (Peripheral Component Interconnect) like PCI, PCIe, or PCI 16
  • PCI is a computer bus for attaching hardware devices in a computer, runs at 33MGH, and is a plug-and-play technology.
  • Plug and play / Zif connectors make life easier as a technician.

• Bus architecture

  • Terminology used for expansion slots
  • You will be installing various cards like network, sound, and video cards. • These include PCI which has a fixed width of 5 bits and can handle 5 devices at a time.
  • Other PCI versions can handle higher rates of transfer. • The Personal Computer Memory Card Industry Association (PCMIA), a popular laptop, supports memory cards, network cards, and removable drives. • AGP (Advanced Graphics Port) also supports your video cards • PCI-X & PCI Express support data lanes to transfer information within bus architecture • AMR (Audio Modem Risers) which ads modem and audio cards • CNR (Communication and Network Riser) which is used for local area networks with audio and modem functionality.

Expansions Solts

Connection and Ports.

• Keyboard & Mouse

  • These connectors allow users to interact with the computer to produce input and outputs.
  • Used to perform operations
  • Typically connected through USB and many are wireless today.

• Serial 1 & 2 Ports

  • Serial and parallel ports are used to communicate with the motherboard.
  • Serial ports send data in series to communication or the COM ports, 1-bit at a time, in a single file.
  • Parallel ports send information 8 bits at a time and can send bits side by side in an operation, rather than a single file.
  • Serial ports are identified as male ports using pins.
  • Most widely used serial communication standard is RS232
  • RS485 is used for multi-line or party-line applications.
  • Current loop is used for a lower data rate with the absence of voltage current.
  • MIL188 is used for military applications
  • Parallel ports are identified as 25-pin hole female connections on the back of the motherboard. Commonly used for printer connections.
  • Many printers will have a DB25 male connector, with 25 pins on one end, and a 36-pin Centronics connector on the other end.
  • Serial 1 & 2 Ports are used to connect devices like: printers, computer displays, GPS receivers, code scanners, POS (Point of Sale ) devices, or even Uninterruptible Power Supplies.


  • USBs are easier because there are no connector pins or screws required and support many modern technologies like: printers, cameras, and recording devices.


You can find free course materials preparing you for the CompTIA A+ exam here:


Authored By Is-Rael Landes

Is-Rael Landes, a good man living on the earth, loving making website, teaching others and coding.

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