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The Motherboard – Part 1

The motherboard is a key part of a computer. Literally, every piece of hardware needs to be plugged into the motherboard. That is the only way to get a communication channel between hardware and computer.

The motherboard contains the wired (traces) that make up the buses: circuits on the motherboard that connect the CPU to other components, 

There are three key items that define a motherboard:

  1. Form factors: they determine the physical size of a motherboard. It also defines the general location of components and ports. 
  2. Chipsets: they define the type of processor and RAM a motherboard requires. 
  3. The build-in components determine the core functionality of your system.

In this post, I will explain these three key items of a motherboard in more detail.

Form factors

Motherboard form factors enable a motherboard to work with cases (the frame of your computer) and power supplies. Form factors have standardized shapes and layouts. This is necessary because otherwise, you need to build a special case for every different form of the motherboard. That isn’t handy because manufacturers want to produce standardized products in order to be able to sell profitable products. The power supply and the motherboard need to have a matching connector and different form factors (motherboard standards) have different connections. 

So shortly summarized, form factors apply to three critical parts of a computer: the computer case (framework), the motherboard itself, and the power supply. These parts are also most responsible for moving air around inside your computer. The form factor defines how air moves around in your computer case and the flow of air (cooling) is extremely important for a healthy computer system. 

There have been a lot of form factors in the past decades like AT (Advanced Technology), ATX (Advanced Technology Extended), and ITX (Information Technology Extended). Nowadays the full names are not used anymore so let’s stick to AT, ATX and ITX for now. 

The AT form factor was invented by IBM in the early 80s and was the standard form factor for motherboards until the mid-90s. AT had its limits, for instance, its limited number of connectors and its lack of flexibility to adapt to changes in technology. This is also the reason why there was an increasing request of the tech community to create a new form factor. with the introduction of its successor, the ATX, the AT form factor became obsolete. I don’t think you can find any computers that have AT nowadays except for museums and collectors. Below you can see such a museum piece:

The ATX form factor was launched in 1995. This form factor was not the king of the hill immediately. It took over the market slowly but in the late 90s, it was the dominant form factor in the market and never looked back. Currently, more than two decades later, ATX is still the dominant form factor. Below is a classic ATX form factor. This is a motherboard from the early 2000s (note the floppy socket that is pretty much redundant these days). However, the setup/form of all motherboards are the same as this one: 

With the ATX, the biggest problem that the AT had, was solved. AT had only a single port for the keyboard but ATX had a complete rear panel that had all necessary ports built-in:

Nowadays, with the increase of USB connections, most keyboards and mouses don’t use the well-known green/purple ports anymore. But at the time this was a huge upgrade compared to AT. In addition to the rear panel, the ATX includes many other upgrades compared to AT. The position of the power supply creates a better movement of air (important for cooling) and the CPU and RAM are in a place that is easier to access. Additionally, the rearrangement of components prevents a possible collision between long expansion cards and the CPU. The ATX form factor is 12×9.6 inches but there is also a smaller version, the microATX. This is a motherboard of 9.6×9.6 inches and is 30 percent smaller than the standard ATX. However, it uses the same ATX connections. MicroATX is also displayed as μATX (μ is the Greek symbol for micro). 

In November 2001, VIA Technologies introduced a small form factor (SFF) motherboard and named it the ITX. The Mini-ITX is 6.7×6.7 inches. This is really small and it competes with the microATX which is almost identical. The biggest advantage of the SFF motherboards is that they only need a very small amount of power to support them. In addition to that, the fan noise is almost zero which is also a very big plus.  


The chipset determines which type of processor your motherboard accepts, the type and the capacity of RAM (Random Access Memory), and the sort of internal and external devices your motherboard supports. There are a lot of different chipsets and they all come with different prices, features, and performance levels. The chipset is a huge factor in the purchase or recommendation of a specific motherboard.

Over a decade ago, chips were originally composed of two primary chips. The North Bridge and the South Bridge. The chip in the North Bridge was responsible for RAM. The South Bridge was responsible for expansion devices and mass storage drives like hard drives. Back then, motherboard manufacturers added a third chip that was called Super I/O chip. This chip handled the interfaces for a variety of low-bandwidth devices (floppy drives, mouse, keyboard, etc.). Nowadays some motherboard manufacturers still add a Super I/O chip to the motherboard. This is then done mainly to deal with legacy devices (read: devices from the past that are still used) so that you can still operate them. Nowadays the terms North Bridge and South Bridge don’t exist anymore. This is how the North Bridge and South Bridge looked like on a classic motherboard:

The CPU is responsible for all controller features that the North Bridge used to do. The primary expansion bus communication is handled by the CPU as well. This was the responsibility of the South Bridge in the past.

Let’s jump back to the expansion devices now. The key question is how they get their Basic Input/Output Services (BIOS). This is provided by software drivers. And the same is the case for modern chipsets. Without software drivers, you can’t create a stable and fully operating computer. If you buy a motherboard, most will deliver an optical disk with drivers, support programs, and additional special features (like antivirus software). Most of the time you can download them from the website as well.

The different chipsets offer support for a lot of different types of hardware, including specific types of memory slots like DDR3 or DDR4, number and version of USB ports, integrated network connections, video support, different types of mass storage devices, and much more. If you are interested in building computers or fixing them it is important to know the most important chipsets in detail. Chipsets define almost every motherboard feature except the CPU itself.

Build-in components

Every motherboard has one or more sockets for a CPU and slots for RAM. These are the standard components of your computer: the heart of everything.

Additionally, there are also ports to support standard mass storage devices like hard drives and Solid State Drives (SSD).


In one of my previous posts about CPUs, you can read that a motherboard is not compatible with all CPUs. For instance, an Intel CPU needs a motherboard that is compatible with an Intel CPU and an AMD CPU needs a motherboard that is compatible with an AMD CPU. You can’t put an AMD chip in a motherboard that is compatible with an Intel chip and the other way around.

Final thoughts

I hope these basics help you understand the importance of the motherboard and how it works. In one of my next posts, I will get into the more advanced features of a motherboard, including the installation of the motherboard.

Feel free to contact me if you have any questions or if you have any additional advice/tips about this subject. if you want to keep in the loop if I upload a new post, don’t forget to subscribe to receive a notification by e-mail.

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