When building a computer there are a variety of parts you need to consider. The planning can be a lot of fun but also poses a daunting task for new PC builders. One of the first and most important decisions you will have to make when building your PC is what kind of computer case to build it in.

In this article, we’ll look at a whole variety of different elements of case design. Hopefully, you’ll learn lots of new terms while reading this guide and walk away from it knowing all you need to know to make an informed decision on your next case.

Motherboard Types and Sizes

The first thing you’ll want to look at most of the time when choosing a PC case is what kind of motherboards it will fit.

The different motherboard sizes determine how much equipment your computer will be able to hold and the case’s overall size.

Most cases that are on the larger side of things will be compatible with all of the smaller sizes of the motherboard as well. For example, an ATX computer case will also be able to hold an mITX and mATX motherboard.


Mini ITX, or mITX, is the smallest of the motherboard form factors. They usually come in at 6.7 inches by 6.7 inches in size making them great for portable PC builds. A mini ITX case will often have design features that facilitate easy transportation such as a handle.

The drawback to these cases is that they often only have room for one expansion card as the motherboards themselves only have 1 PCI-E slot. A mini ITX case will also only be able to support two sticks of RAM.

Overall, these motherboards are best for computers on the go, but will not be a gaming powerhouse.


Micro ATX, or mATX, is the next size up from mITX and measures 9.6 by 9.6 inches. Micro ATX cases are still on the portable side of things, but usually boast significantly more hardware space than mini ITX cases.

These motherboards step up the number of PCI-E slots to four allowing you to run graphics cards in SLI or Crossfire. They also feature more RAM slots than the mITX boards with four slots for memory rather than only two.

While not the smallest, mATX cases present a nice balance between portability and performance.


ATX motherboards are the standard in most cases. An ATX case can range quite a bit in size depending on its intended purpose, but will rarely be considered portable.

ATX motherboards are 12 inches by 9.6 inches and have all the features needed for a high-end computer. Like the mATX boards, ATX motherboards can hold up to four sticks of memory making them viable for workstation use.

Full-size ATX motherboards have up to seven PIC-E slots. This allows you to fill an ATX case with soundcards, graphics cards, network cards, and more.


mITX, mATX, and ATX will make up about 90% of the motherboards and cases you’ll see. Sometimes, however, you’ll see a rare configuration such as the extended ATX, or EATX.

EATX boards are essentially anything larger than ATX and often come in at 13 inches by 12 inches but can also be smaller than that. These boards usually carry a special set of features that would not otherwise fit on a normal motherboard.

Sometimes this can include even more PCI-E slots, special CPU sockets, or even multiple CPU sockets.

These are not typically something the average person or gamer will be looking for. EATX motherboards are typically designed for intensive workstations workloads. This could include video editing or 3D rendering.

Case Form Factors

Next, once you know what kind of motherboard you will need, it is time to decide what form factor of case you’ll want. There are generally four different terms used to describe a case’s form factor, but these terms aren’t standardized across the industry and can often have some slight variations.

Small Form Factor (SFF)

Starting with the smallest form factor we have what are simply called small form factor cases, or SFF.

SFF cases will typically only be able to fit an mITX motherboard. This means they will only have room for one expansion card, if any. Some cases at this size will ditch expansion slots altogether in an effort to take up an absolute minimum amount of space.

These cases are often less than a foot tall and will sometimes even be cube-shaped. These are best for people who prioritize portability or compact size over performance. Not only will the amount of hardware you can fit into the case be limited, but cooling will also be less than ideal.


Next up are the mini-tower cases. These cases are usually 14 to 16 inches in height and are almost always designed to be used with an mATX motherboard.

This means they can fit one GPU easily, but will rarely be able to handle two GPUs. Even if you could fit two graphics cards into the case the airflow and cooling might not allow them to run properly.

Mini-tower cases present a balance of compact size and decent performance.


Mid-tower cases are the most common cases on the market. This style of case will typically stand between 17 and 21 inches tall and fit a standard ATX motherboard.

With their ATX motherboard, these towers are fully capable of multi-GPU configurations. There is both space in the case as well as sufficient airflow to run cards in SLI or Crossfire.

These cases typically have all the features you’ll need when building a workstation or gaming PC. They’ll have full-fledged cooling, plenty of drive bays for storage, and enough room for full-size graphics cards.


Finally, the largest cases will fall into what is called a full-tower form factor. These cases are usually between 22 and 27 inches in height and are designed for those who need a little something extra.

Whether you plan to make a huge water cooling loop, or need tons of drive bays to store a massive library of games and videos, these cases have the space you’ll need.

Full-tower cases are also the easiest to work in thanks to their roomy interior. If you have large hands or find working in smaller cases a hassle, you might appreciate a big case like these.

Cooling and Airflow

Now that we’ve looked at the differences between motherboards and case form factors, we’ll talk about some things that are more specific to individual cases.

One thing that is very important to consider depending upon the hardware you’ll be putting into your case is how good the cooling options and airflow of the case are. Keeping your PC parts cool is important for both performance and lifespan.

If a computer component runs too hot it will “throttle” itself. This means that it will automatically slow itself down to prevent from overheating and causing damage.

Obviously, we want to avoid this at all costs. If you have equipment that runs especially hot like a CPU with tons of cores then you’ll want to take airflow and cooling into careful consideration.

One thing to look for when determining whether a case has good airflow and cooling potential is how many fan mounts it has. A case with only one or two fans will not be effective at cooling high-end equipment. On the other hand, a case with five or more fans will offer tremendous cooling.

It is also important to look at how many radiators a case can hold. Radiators are an essential part of water cooling and are used to dissipate the heat that the water in the loop picks up from the CPU or graphics card. These radiators need to be mounted somewhere on the case that allows them to get fresh air.

Radiators come in a variety of sizes, so if you plan to use water cooling make sure your case can accommodate the size of radiator you plan to use.

Types of Fans

It is also important to note that there are several varieties of fans.

The first thing that differentiates different types of fans is their size. Fans typically come in 120mm, 140mm, and 200mm sizes. Larger fans will obviously push more air. Different fan mounts in a computer case will be intended for different sizes of fans, so make sure you are getting the right fans for your case’s mounts and vice-versa.

The other thing that differentiates fans is whether they are airflow optimized or static pressure optimized. Most of the fans that a computer case comes with are airflow optimized. This means that they are designed to move as much air as possible.

This is great for case fans that are intended for cycling the volume of air in the case as quickly as possible. However, these fans are not the best choice for putting on a radiator or heatsink.

Fans that are designed for these purposes are static pressure optimized. This means that they can blow the air with more force allowing it to more easily move air over the fins of a heatsink or radiator.

Front I/O

A term you’ll commonly see when shopping for computer cases is “front I/O”. This stands for front input and output and refers to the ports and jacks on the front of your case.

The importance of front I/O varies depending on how you plan to use your computer. Almost all cases will come with a standard headphone and microphone jack on the front.

Aside from audio jacks, most cases include some USB ports as well, but the type and number vary greatly. If you plan to frequently use flash drives, multiple keyboards, mice, or other peripherals, then a case with lots of USB ports on the front could be nice.

There are also different types of USB ports to watch out for. USB 3.0 is the most recent standard for normal USB. USB 3.0 ports are reverse compatible with 2.0 and can transfer information much faster. The transfer rate of USB 2.0 is capped at 480 megabits per second, while 3.0 has an astounding 5 gigabit per second transfer rate.

This can be super useful if you need to transfer large files often and want to save time. Most people will want to make sure their case has at least two USB 3.0 ports, and more if they plan to use lots of peripherals at once.

There are also USB 3.1 Type-C ports on the front I/O of some cases, which are even more modern than USB 3.0, but are not reverse compatible. These plugs are used on the latest smartphones and feature a totally different shape from older USB ports. They are oval and reversible rather than square. You might want a case with one or two of these if you plan to be using your case for many years into the future.

Drive Bays

The next factor to look at when choosing the right computer case is drive bays. Drive bays come in three sizes; 2.5″, 3.5″, and 5.25″.

5.25-inch bays are sometimes referred to as “external bays”. These large drive bays are intended to be filled with disc drives. These can include CD, DVD, and Blu-Ray readers and writers. While these are relatively irrelevant in today’s era of digital download, some people still might want to take these into consideration.

3.5″ and 2.5″ bays are designed for storage. 3.5-inch bays are intended to hold traditional hard drives. These drives use spinning platters inside an enclosure to store your data. This makes them slow compared to more modern forms of storage, but they typically hold more data and are more affordable than other forms of storage.

2.5″ bays are designed to accommodate solid-state drives, or SSDs. An SSD does not use any moving parts. Instead, solid-state drives use what is called NAND storage which allows them to operate at much higher read and write speeds than hard drives.

Depending on how much data you plan to store take into account how many drive bays you will need. As a rule of thumb, you can easily store one or two terabytes on a 3.5-inch drive, and 250-500 gigabytes on a 2.5-inch drive.

Power Supply Unit

The next thing to look at is what kind of power supply unit, or PSU, your case can fit. The power supply is responsible for providing the components in your PC with a steady supply of power at the right voltage and current.

This is, of course, an incredibly important job, as any slip up could kill your hardware. Most cases will be able to accommodate an ATX power supply unit. These are the standard size power supplies and are easy to find.

Smaller cases will sometimes need to use somewhat rare SFX form factor power supplies. Even smaller cases will often use proprietary power supplies, but these more often than not come with the case itself.

Different power supplies will feature different numbers of connectors. Make sure if your case comes with a power supply that it has the right types and quantities of connectors to run all the hardware you plan to use.

Different power supplies will also offer varying amounts of voltage and efficiency. Use a tool like pcpartpicker to determine how much voltage your PC will need.


Computer cases not only come in all shapes and sizes, but also all sorts of different materials.

The most common material used in most cases is plastic. Plastic is inexpensive which allows manufacturers to keep their costs down. It is also fairly durable and relatively lightweight.

Some high-end cases, however, opt for the use of metal as the main material in their case. While metal cases are much heavier than plastic ones, they are significantly more durable. Metal also insulates sound in the case better than plastic can. At the same time, metal conducts heat away from the computer’s internal components more than plastic.

Another material you’ll often see in cases is tempered glass. Glass windows became a popular feature for many cases a few years ago and allow you to show off the hardware in your machine without having to open it up.

A common alternative to glass windows is a clear plastic window. Plastic won’t shatter if dropped or mishandled, but is not as clear as real glass. Plastic is a safer alternative for those who want to see their hardware, but don’t want the added risk and weight of glass in their PC.

The final material that you should look for in your case is rubber. Rubber is often used for sound dampening to prevent your computer from making too much noise when it’s hard at work. Look for rubber not only on the feet of the case, but also on the fan mounts.

Fans will produce about 80% of the sound your computer makes, so insulating these with rubber will significantly reduce the amount of sound your computer produces.

Cable Management and Headers

When building a custom PC, cable management is important to consider. Cable management is a broad term that describes how well the design of the case allows you to clean up the wires inside the case.

Cleaning up the mess of wires in a case is not only important if your case has a window. Aside from the obvious aesthetic purposes of cable management, properly channeled cables help aid in good airflow inside the case.

If you have a big ball of cables somewhere in your case it can restrict the airflow either entering or leaving the case. This will force your fans to work harder, push your temperatures up, and lead to slower performance.

To avoid this, look for cases that have rubber grommets behind the motherboard. These allow cables to be easily passed through from the back to the front of the case. Also look for cases with a PSU shroud. This will cover your power supply and help channel cables to where they need to go without cluttering the case.

Also, make sure your motherboard has the right types of headers. Headers are what connect the front I/O of your case to your motherboard. If you have USB 3.0 on your case, make sure your motherboard has a USB 3.0 header. Likewise, if your case has USB 2.0 ports make sure your motherboard has a USB 2.0 header, etc.

Expansion Card Slots

The last thing we’ll tell you to take into consideration is the number of expansion card slots that your case has. These slots are small openings in the back of the case that allow access to the rear I/O.

This can include the video outputs of graphics cards or the audio output of soundcards among other things. If you plan to use multiple graphics cards in an SLI or Crossfire configuration then you will need at least two of these slots.

More likely than not your graphics card will actually occupy two of these slots rather than one, meaning you might even need four of these slots in a multi-GPU setup. Additionally, these slots are taken up by network cards, sound cards, and some other devices.

Make sure you plan accordingly and choose a case that has enough expansion slot cards to support all the PCI-E slots on the motherboard you plan to purchase. A standard mid-tower case that is designed for an ATX motherboard will have six or seven of these slots, which is plenty for the average gamer and will work with high-end rigs.


Hopefully, this lengthy overview has armed you with the knowledge you need to choose the right case for your needs. The components of this article are generally written in order of importance, so as you shop around for cases make sure to go through each of the elements of this list in order and determine how important each one is to you.

If you have any questions that you feel weren’t answered in this article, we encourage you to comment down below and we’ll do our best to answer your questions. Also, if you’re looking for more information there are a variety of product reviews and lists on our site that you can find that will give you even more information about specific cases.

These lists are full of information and are sure to give you some great ideas for which case is best for you.


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