4 Different Types of Motherboard & PC Case Size Or Computer

When it comes to researching and purchasing a PC, you may encounter the terms form factor and case size. While it may seem like a minor detail, understanding these concepts can be crucial if you plan on upgrading or building your own PC in the future. In this article, we’ll break down everything you need to know about form factors and case sizes.

What is Form Factor?

To begin, let’s distinguish between form factor and size. Form factor refers to a specific standard that a component adheres to, while the size is self-explanatory. In the context of computers, the term form factor usually applies to the motherboard, which serves as the foundation of your PC. It connects and enables the communication between all the other components. The motherboard form factor also specifies other details such as the positioning of expansion slots, power requirements, and how the board is mounted to the case.

Types of Motherboard & PC Case Size

There are four main motherboard form factors on the market today:

  1. Mini-ITX (mITX),
  2. Micro-ATX (mATX),
  3. ATX,
  4. Extended ATX (eATX).

While there are other form factors available, these four are by far the most common. Each form factor is a different size and comes with its own unique advantages and disadvantages.

ATX motherboards

Let’s take a closer look at ATX motherboards, which are easily the most prevalent form factor measuring 305 mm x 244 mm. Introduced by Intel in 1995, the ATX form factor has remained unchanged in shape despite significant advancements in technology. However, the beauty of ATX compatibility lies in the fact that even if you have an ATX-compatible case from the last millennium, you can still easily install a modern motherboard without requiring any modifications.

If you’re planning on upgrading or building your own PC, it’s important to select the appropriate form factor and a case size that will accommodate all of your components. With this guide, you should be able to navigate these details with ease and ensure a successful build.

Micro ATX Motherboards

Micro ATX Motherboards, with their dimensions of 305 mm x 244 mm, represent the most widely adopted motherboard form factor. The ATX, or Advanced Technology eXtended, the format was initially launched by Intel in 1995, and despite significant technological advancements, its shape has remained unaltered. This stability means that if you have an ATX-compatible case that dates back to the last millennium and want to integrate a modern motherboard into it, no modifications are necessary.

ATX form factor motherboards provide numerous slots and ports for expansion. Typically, you can expect four slots for RAM and up to seven PCI Express slots. These boards offer an abundance of storage options too, with most modern models featuring approximately six SATA ports and a couple of M.2 slots.

For most users, an ATX motherboard can provide far more functionality than required. A decent gaming PC requires a GPU (one PCI Express slot), a 1 TB M.2 drive, and 16 GB of RAM, leaving ample room for future expansion.

In the past, PCs used to have multiple hard drives, DVD burners, sound cards, network cards, and more, but nowadays, most of these requirements are integrated into the motherboard’s chipset. Additionally, most components are smaller than they used to be.

If you are comfortable with a larger case that takes up more space, an ATX motherboard is a reliable choice for your PC. Due to its popularity, there is a vast selection of ATX motherboards on the market, encompassing a wide range of prices and specifications.

Mini ITX Motherboards

Mini ITX Motherboards, measuring a mere 170 mm x 170 mm, were introduced in 2001. The mounting holes are the same as those on an ATX motherboard, and all the expansion slots and backplates align as well, enabling an mATX motherboard to fit into a case designed for ATX or mATX with ease.

The most significant advantage of the mITX form factor is that it can fit into much smaller spaces than other motherboard standards. As such, mITX motherboards are ideal for PCs where space is limited, such as home cinema PCs or desktop computers that need to be hidden away.

However, expansion options for mITX motherboards are severely limited. These motherboards have a maximum of two RAM slots and a single PCI-E slot, in addition to fewer SATA and M.2 ports for storage. Despite these limitations, mITX motherboards can still be used for powerful applications like gaming PCs, provided that you choose the appropriate case and balance the space-saving advantage against limited expandability.

Smaller motherboards, such as Nano- and Pico-ITX, exist in the market but are less common and more specialized, typically utilizing unconventional processors and components.

Extended ATX Motherboards

Extended ATX Motherboards, or eATX, are a larger variant of the standard ATX board, measuring 305 mm x 330 mm, with even more space for expansion. Although these boards are less common and more expensive, they can be invaluable in specific use cases that require additional slots.

eATX motherboards often (but not always) double the number of RAM slots to eight and have a higher maximum memory capacity, meaning that the chipset can handle more RAM. Most current ATX boards are limited to 64 GB; eATX motherboards can accommodate up to 128 GB of RAM. Additionally, eATX motherboards provide more SATA and M.2 ports and more PCI Express slots than their ATX counterparts.

However, unless you genuinely require all that space and power, a good-quality ATX build is probably a better choice. With an ATX build, you can allocate more of your budget towards better CPU, GPU, and RAM or a few games to get you started.

Types of Motherboard & PC Case Size

Motherboards must adhere to specific form factors, but cases have no such restrictions. They can vary greatly in both size and shape, each with its own advantages and disadvantages. There are several common shapes and styles of PC cases to choose from.

Full tower

Full tower cases 55- 75 cm tall and 22 – 32 cm in width are ideal if you need the ultimate in expandability and power, with space for an eATX motherboard, multiple graphics cards, and abundant storage. They also accommodate the largest and most powerful cooling systems.

Mid Towers

Mid Towers 35- 55 cm tall and 15 – 25 cm in width are the most popular and widely used computer cases, with acceptable overall dimensions that can accommodate almost all types of motherboards and full-size components such as video cards over 300mm long. Mid Towers have a length of about 31 cm, making them easy to install with two to three expansion slots thick.

Mini tower

Mini tower cases 30 – 45 cm tall and 15 – 25 cm in width are perfect for those who need a smaller PC that doesn’t compromise on performance. They are designed around mATX motherboards and have all the space you need for a powerful PC. They can accommodate full-size graphics cards, plenty of RAM, an SSD, and a good cooling system.


Desktop cases were once the standard shape for PCs, but they have become less popular since the introduction of lightweight flatscreen technology. However, they can still be the best solution for certain uses. They are usually designed for mATX or mITX motherboards and are slimmer than tower cases, making them versatile if your space is limited.


Small form factor cases are designed to slot into tight spaces and are generally designed around mITX form factor motherboards. They take up much less space than their larger counterparts and can be a great option if space is limited and you’re not planning to play power-hungry games.

HTPC and SFF cases were considered niche, but their popularity has grown due to the miniaturization of powerful components. HTPC is perfect for home multimedia entertainment, while SFF is an excellent alternative to laptops as they offer more power at less cost.

If you need something really tiny, then an ultra-small form factor computer is just the ticket. These are still built around a proper CPU and will run Windows natively, so they will do everything a low-spec bigger PC will, just in a much smaller space.

All-in-one PCs house

All-in-one PCs house all the components in a slightly expanded monitor casing. They are brilliant if you need something to sit on a desktop but are really restricted for space. However, there will be no space inside for expansion beyond the option to swap out RAM or SSDs for larger versions.

In conclusion, the type of PC case that is right for you depends on the space you have and what you want to use it for. If you want to play up-to-date games, you’ll need a reasonably big case with a motherboard that allows for the components you need. For more everyday use, a smaller form factor is likely sufficient. If you need a computer with huge RAID arrays or multiple graphics cards for rendering or gaming, then a full tower case may be necessary. If you’re not sure which type of case is right for you, contact a team of experts who can help you determine the best fit for your needs.

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