The motherboard is the main component of a computer. It is the circuit board that all the other components of the computer connect to. It holds the CPU and memory as well as the connectors for the power supply, hard drives, and other peripheral devices. The motherboard is what connects all these components in a system that functions as a computer. It is typically the second component chosen when building a computer after the CPU.

Here are some of the typical interfaces and components you will find on a motherboard:

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Every computer has a motherboard. You usually can see what type of motherboard a computer has in its computer specs. The type of motherboard determines what type of components your computer can use and the limits of upgrading the computer in the future.

Motherboard

Motherboards also have a specific size, shape, layout, and mounting hole pattern. If you are building a computer, this is important to know also, because computer cases are only designed for specific sizes of motherboards.

Types of motherboard form factor

Desktops, laptops, tablets, smartphones, and other categories of computers all have motherboards, but usually when we are talking about motherboards, we mean those made for desktops. Motherboards for desktop computers follow standards called form factor so that computer manufacturers know exactly what size case they need to build, what type of CPU to use, and what type of peripheral components they need to build a computer with specific specs. This makes motherboards of the same form factor interchangeable even when they are manufactured by different companies. The motherboards for other devices like laptops are proprietary and are usually not upgradeable like those of desktops.

Here are some of the common types of motherboards:

XT Motherboard

This was the first motherboard form factor and was short for eXtended Technology. You won’t run into these anymore unless you are dealing with vintage computers. IBM created it in 1983, and because IBM published the specs and made them open, many manufacturers used it as a standard. This motherboard weighed 32 pounds and was designed for business users.

AT Motherboard

The AT form factor was also designed by IBM. AT stands for Advanced Technology. It was a much smaller design and looked more like the motherboards we are used to seeing. It was the common form factor for computers in the 1980s. This motherboard is also known as the Full-AT.

The AT motherboard was about 12-by-38 inches, which means it won’t fit in a mini-desktop, which should have a footprint no larger than 8-by-8 inches. The dimensions of this motherboard made it difficult to install the new drives and access various connectors. For motherboards of this type, six-pin plugs are used as a power connector. Because the power connector sockets are difficult to distinguish, many users fail to connect their devices properly, causing damage.

AT boards had both serial and parallel ports that attached to the case through an expansion slot and used cables to connect to the board. Parallel ports are no longer used in modern motherboards. They also had a single keyboard connector that was soldered to the back of the board. The processor sat at the front of the board and sometimes could get in the way of the expansion slots. The SIMM slots for memory could be located in various places on this type of board, but are most often found on the top of the board.

This motherboard served users well from the Pentium p5 to the time when the Pentium 2 was introduced. It was designed for the Intel 80386 architecture, which became obsolete with the introduction of the Pentium 2. It was retired by IBM in 1995.

Baby AT Motherboard

This motherboard was another flavor of the AT motherboard. It was called “baby” because it was smaller than the full-sized AT motherboard and measured 8.5-by-13 inches, but the size could vary slightly between manufacturers. The smaller size of this motherboard made it easier for technicians to work on it because there was more room inside the case. Other than that, it had similar features to the standard AT motherboard.

ATX Motherboard

Intel released the ATX motherboards in the mid-1990s as an improvement on the AT motherboards that were used previously. Motherboards of this type differ from their AT counterparts in that they allow the interchangeability of the connected components. Additionally, because the dimensions of this motherboard are smaller than those of AT motherboards, there is sufficient room for the drive bays. The connector system of the board was also improved. On the back plates of AT motherboards, additional slots were provided for various add-ons.

This motherboard is still in use today, is the most popular motherboard ever, and many other form factors were based on it. Some of the features that come on the ATX motherboard include:

Micro-ATX Motherboard

The Micro-ATX board is similar to the ATX board. The only real difference is its size. It is 9.6-by-9.6 inches instead of 12-by-9.6 inches. This board was made for small computer cases. Because it is smaller, it has less expansion and memory slots than the ATX board. Just because they are smaller doesn’t mean they are less capable of providing computing power. These boards are used in even some gaming computers.

E-ATX Motherboard

The E-ATX or extended ATX motherboard is much larger than the standard ATX motherboard. This motherboard is primarily used for gaming where a lot of power is needed. Most of the extra space on the board is used for extra expansion slots and memory slots. The boards also have built-in Wi-Fi, sound cards, and onboard troubleshooting features. Up to 128 GB of RAM can be installed on this board.

LPX Motherboard

Low profile extension motherboards, or LPX motherboards, were created after the AT boards in the 1990s.

The main difference between these boards and previous ones is that the input and output ports are located at the back of the system. AT boards also adopted this concept in their newer versions as a result of its success. Additional slots were also placed with the use of a riser card. However, these riser cards also posed the issue of insufficient airflow.

In some cases, the LPX board did not even have a real AGP slot, and instead connected via the PCI bus. All of these unfavorable aspects led to the extinction of this motherboard system, which was replaced by the NLX.

NLX Motherboard

The NLX board is an upgraded version of the LPX motherboard. It was created in the 1990s to provide support for larger cases, cards, and devices. NLX stands for New Low Profile Extended. It supported the Pentium II processor, AGP, DIMM memory, and USB.

BTX Motherboard

BTX stands for Balanced Technology extended.

A major goal of the BTX was to remove or avoid some issues that arose when using the latest technologies. Newer technologies tend to draw more power and release more heat than those running on motherboards that conform to the ATX specification of 1996. Intel proposed both ATX and BTX standards. Intel canceled the development of BTX retail products in September 2006 due to its decision to focus on low-power CPUs after having issues with scaling and temperature with the Pentium 4.

Gateway Inc. was the first company to implement BTX, followed by Dell and MPC. Apple’s MacPro uses some BTX elements, but it is not BTX compliant. Compared to previous technologies, this type of motherboard has some improvements:

Pico BTX Motherboard

A Pico BTX motherboard form factor is for the manufacture of even smaller BTX standard cards. This is smaller than many current “micro” sized motherboards; hence the name “Pico” has been used. These motherboards share a common top half with the other sizes in the BTX line, but they support only one or two expansion slots, designed for half-height or riser-card applications.

Initially, the ATX and BTX motherboards were so similar that moving a BTX motherboard to an ATX case was possible. In later stages, the BTX form factor was transformed into a mirror image of the ATX standard. When compared to ATX, BTX motherboards are ‘left side up’ and not upside down. This means they are mounted on the opposite side of the case. Various computer cases, for example, the Cooler Master Series (Stackers), were released so that users can develop motherboards without buying a new case. However, all connectors and slot standards are identical, including PCI(e) cards, processors, RAM, hard drives, etc.

BTX power supply units can be exchanged with ATX 12V units, but not with older ATX power supplies without the extra 4-pin 12V connector.

Mini ITX Motherboard

The Mini-ITX form factor is a 6.7-by-6.7 inches low-power motherboard size. It was designed by VIA Technologies in 2001. These are largely used in small form factor (SFF) computer systems. Mini-ITX boards can also be cooled easily because of their low power consumption architecture. Such an architecture makes them widely useful for home theater PC systems or systems where fan noise can diminish the quality of the cinema experience. The four mounting holes in a Mini-ITX board line up with the four holes in ATX specification motherboards, and the locations of the back plate and expansion slot are the same. Although, one of the holes used was optional in earlier versions of the ATX. Hence, Mini-ITX boards can be used in places that are designed for ATX, micro-ATX, and other ATX variants if required.

One expansion slot is provided for the Mini-ITX form factor, which corresponds to a standard 33 MHz 5V 32-bit PCI slot. Some cases use riser cards, and some even have two-slot riser cards, even when the two-slot riser cards cannot be used with all the boards. Several boards based on non-x86 processors have a 3.3V PCI slot, and the Mini-ITX 2.0 (2008) boards have a PCI-express ×16 slot. PCI riser cards supplied with cases cannot be used with these boards.

Nano ITX Motherboard

This motherboard is even smaller than the Mini ITX board. It measures 4.7-by-4.7 inches. These are fully-integrated boards that are designed to consume very little power. It can be used on many devices but is generally found in smart entertainment devices like smart TVs, in-vehicle devices, media centers, PVRs, and more.

Pico ITX Motherboard

This motherboard is the smallest form factor in this article. A Pico ITX motherboard only measures 3.9-by-2.8 inches. or about 75% smaller than the Mini ITX. VIA technologies designed this board for the IoT market, where devices are becoming even smaller as the years go on. It is an x86 based platform and has low power consumption. It is a good choice for embedded systems like in-vehicle computers, industrial automation, digital signature, and more.

Conclusion

Now that you know about motherboards, including some historical boards that are no longer in use, you have an idea of which to use to build your dream PC or even an IoT device. Motherboards have come a long way since the old IBM XT board. Choosing the right motherboard is an important part of building your PC. A good motherboard can last for many years and through many upgrades as long as you planned for that. You can swap out your CPU, add more memory, upgrade your GPU, add more hard drives, and make other changes as technology improves. How far you take your upgrades depends on your motherboard choice.

Page Last Updated: September 2021

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