You’ve probably heard the term “motherboard” when dealing with computers. In basic terms, it’s the flat board where most of the system’s operations are executed through chips, ports, and slots.

Technical enthusiasts probably know the role of each of these motherboard components. Others don’t know or care as long as their computer works. However, if something goes wrong, a basic knowledge of the motherboard parts and functions is required. 

The history of motherboards

Before motherboards were invented, individual computer components were fused onto separate circuit boards. These were plugged into a backplane at the rear of the machine. Together, they served as a common link to efficiently operate the computer. 

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This changed in the early 1980s. Computer manufacturers such as IBM wanted a better solution to make their machines smaller, particularly if they wanted to break into the personal computer (PC) market.

So, in 1981, IBM introduced the first motherboard. Originally called a planar or breadboard, it consolidated the functions and parts of other circuit boards. As a result, a flat board installed within a PC’s casing handled most of its operations. For IBM, it was a perfect solution when it released its first personal computers later that year. 

Motherboard and central processing unit

The basics of motherboards

Though technology has significantly changed, the concept of the motherboard remains the same. Basically, it’s a computer’s main printed circuit board (PCB). Over the years, it has also been called the mainboard, main circuit board, and logic board, among other names. 

The composition of motherboards

The base of a motherboard is composed of two materials.

Each motherboard is made in layers to save space. Four to eight layers of copper-embedded fiberglass PCBs equal one motherboard. This both saves space and, since electrons don’t travel long distances, increases processing data.

The individual boards are attached to each other with a resin. Next, the top and bottom sides are coated with copper. This is followed by a layer of light-sensitive “photoresist” material. 

The nearly finished board is exposed to UV light. It’s washed to remove uncovered remnants at the copper layer. At this point, the motherboard’s operational materials are installed via surface-mount technology (SMT).

There, the circuit boards are stacked and moved to an advanced printer. Via a pre-programmed layout, the motherboard’s required components are soldered in place. A manual inspection of the PCBs that come out of SMT ensures they are accurate.

Prior to extensive testing, the motherboard goes through a dual inline package (DIP) process. It’s placed in a machine that installs small capacitors that store electrical energy. Then, 24-pin connectors and ports for a basic input and output (I/O) system are added. Finally, they are placed in a high-heat chamber to reinforce the resin and attached components. 

Motherboard components and functions

Standard components are installed on close to two dozen slots on the motherboard for basic computer operations. Here’s a breakdown of the most critical:

CPU socket

This is where the central processing unit (CPU) is installed. This center of the motherboard is the computer’s “brain,” where data is processed and transferred. 

If you have looked at a Task Manager window on your machine, you might see a CPU category. When this is close to 100 percent, it means the unit is processing and transferring large amounts of data. Sometimes, updating the operating software or cleaning up the data corrects this. If that fails, then a stronger CPU might need to be added.


The basic input-output system (BIOS) and complementary metal oxide semiconductor (CMOS) are critical components that maintain regular operations when the computer is active or unpowered. The BIOS chips store all the motherboard’s settings. Sometimes, computer manufacturers release updates to increase the component’s operational capacity. 

The BIOS chip contains a basic code that takes a computer through the boot process. This starts with a boot loader. Next, the operating system (OS) kernel is initialized. As long as there are no issues, the OS takes over. 

This chip requires constant power to function, which is where the CMOS comes in. The small battery maintains the data’s integrity when the computer is shut down or unplugged. Should the CMOS fail, the system can lose vital data concerning hardware and disc drives. When this happens, an OS error occurs. 

Power connector

The power connector is where the main power supply is attached. This generates power for the motherboard and all its components. Normally, 20 or 24-pins compose the connection. Newer models have additional four- and eight-pin connectors to supply additional power. 

Voltage regulator module

A voltage regulator module (VRM) is also known as a processor power module (PPM). It has a similar operation mode as the computer’s power supply unit (PSU). The VRM’s job is to reduce the electronic potential between two points. As a result, it provides the CPU with the amount of voltage it needs. 

There are two parts of a VRM system on the motherboard. The first is metal-oxide-semiconductor field-effect transistors (MOSFET). These are recognizable as flat rectangle components normally located around a CPU socket. The MOSFET provides the CPU with the exact voltage it needs. 

The second component are chokes, which sit beside the MOSFET. Their job is to stabilize currents and capacitors if a sudden voltage spike takes place. Motherboards that have a strong resistance to electrical surges contain several chokes. Each one equates to better stability.

It’s important to have a high-quality motherboard with strong VRMs if you intend to overwork your CPU with games or large uploads/downloads of data. It should have at least eight chokes or more to withstand potential spikes. Chokes are usually located beside the MOSFET and stabilize the currents and capacitors if there is a sudden voltage spike.

Memory slots

Located on the motherboard’s right-hand corner, memory slots house the random access memory (RAM) modules. The number of slots varies depending on the board model. It can be as low as two and as high as eight slots. 

Memory is a principal component to maintain your computer’s functionality. Generally, memory modules are temporary storage. They receive stored data that is read and acted on almost instantaneously. For instance, an executed program becomes temporarily stored in these modules.

Memory slots on modern computers take:

Several memory slots are left blank on most motherboard models. This allows users to expand their computer’s temporary storage capacity if needed. Needless to say, you need to review your system’s configurations to determine what version of RAM it takes.

Recently, RAM-only servers and laptops have been introduced into the market. These systems don’t have hard drives. Rather, the memory is handled differently to temporarily store data and completely remove it during a soft or hard reboot. Google’s Chromebook is a modern example of a RAM-only computer.

ROM chip

While RAM cards are temporarily used to store data while the computer is active, read-only memory (ROM) chips are critical to the device’s start. It’s where information needed to kick off initialization processes is stored. Furthermore, ROM retains its contents when the machine is shut down. Conversely, data stored in RAM is lost when the computer is shut down. 

Video card slot

The video card slot is used for a circuit board that handles images and colors on a desktop or laptop. In modern motherboards, this takes the form of peripheral component interconnect express (PCI-Express). It permits quicker processing and sharper images than the previous accelerated graphics port (AGP). 

Motherboards on lower-end PCs might have embedded components rather than a video card slot. On the other hand, high-end gaming systems come with multiple slots for enhanced graphics.

Ports available on a video card might include ones for:

Audio card slot

The cards that fit into these motherboard slots convert electrical signals to audio. Depending on what a computer manufacturer offers, different types of ports are in the rear of a PC’s case or back of the laptop. Normally, these are related to I/O ports, so there are several 3.5mm options used for a microphone, external speakers, audio recorder, or a game joystick.

Expansion slots

Motherboard expansion slots allow you to add new PCI-compatible components. These tend to expand a PC’s functionality. Some examples that might be added are:

The number of expansion slots depends on the motherboard’s design. As opposed to standard models on PCs and laptops, larger models have more slots available.

Northbridge and southbridge 

At the lower-right bottom of modern motherboards is a square piece of metal called a heat sink. It provides thermal protection for the northbridge and southbridge, which are critical in maintaining proper computer operations.

The northbridge coordinates data flow among the memory, the video card, and the CPU. A second chip, known as the Southbridge, handles the data flow among the processor and peripherals such as sound or network cards.

Today’s CPUs have a built-in northbridge. This allows them to operate more quickly and reduce the latency seen on older computers. The southbridge chip is still on the physical motherboard. It’s usually covered by the heatsink. Therefore, its temperature remains steady during normal PC operations. 

Front I/O connectors

These connectors are where items such as the power switch, LED power indicator, and reset switch exist. Additionally, these connectors handle audio and USB ports. Normally, they’re located along the bottom of the motherboard.  

IDE and SATA ports

Integrated drive electronics (IDE) and serial advanced technology attachment (SATA) ports provide connections for a storage device. This includes an optical drive that plays and writes to CDs, DVDs, and Blu-ray discs. Also known as rear I/O connectors, older motherboards contain IDE ports. Conversely, SATA interfaces, which are faster, are the new standard. 

It’s not uncommon for today’s manufacturers to include SATA revisions on their motherboards. The reason is optical drives on the market aren’t bandwidth hogs like an internal or external solid-state hard drive.  That’s why a motherboard might contain a mixture of second and third-generation SATA ports.

These ports tend to be color-coded to represent different peripherals. For instance: 

Network card slot

The network interface card (NIC) is added to the network card slot. This connects to an RJ-45 port in the rear of the computer. This has a similar shape to an old-style phone jack. It is used to connect to a local area network (LAN) or the internet.

Modem card slot

Though modems are an older technology, motherboard manufacturers still include a slot for this equipment. With connectors in the rear of the computer, users can connect to a telephone line to access the internet. 

Overall, the motherboard in your computer makes everything go. If one slot or connection starts to falter, it can affect the device’s speed, storage, and general usefulness. Therefore, it’s of the utmost importance to regularly maintain it.

This doesn’t mean opening up your computer and cleaning everything. Rather, keep it in a climate-controlled space. Remove dust and dirt from its exterior when possible. If something needs to be replaced, then seek out a professional. Have questions about a specific motherboard? You might just find the answer in this blog on the most popular motherboard types

Page Last Updated: August 2021

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