What Is a Computer Case?

Explanation of a computer case

The computer case serves mainly as a way to physically mount and contain all the actual components inside a computer, like the motherboard, hard drive, optical drive, floppy disk drive, etc. They typically come bundled with a power supply.

The housing of a laptop, netbook, or tablet is also considered a case, but since they aren't purchased separately or very replaceable, the computer case tends to refer to the one that's part of a traditional desktop PC.

Some popular computer case manufacturers include Xoxide, NZXT, and Antec.

NZXT H210i Desktop Computer Case
NZXT H210i Desktop Computer Case (Side View).


The computer case is also known as a tower, box, system unit, base unit, enclosure, housing, chassis, and cabinet.

Important Computer Case Facts

Motherboards, computer cases, and power supplies all come in different sizes called form factors. All three must be compatible to work properly together.

Many computer cases, especially ones made of metal, contain very sharp edges. Be very careful when working with an open case to avoid serious cuts.

When a computer repair person says "just bring the computer in," they are typically referring to the case and what's inside it, excluding any external keyboard, mouse, monitor, or other peripherals.

Why a Computer Case Is Important

There are several reasons why we use computer cases. One is for protection, which is easy to assume because it's the most obvious. Dust, animals, toys, liquids, etc. can all damage the internal parts of a computer if the hard shell of a computer case doesn't enclose them and keep them away from the outside environment.

Do you always want to be looking at the disc drive, hard drive, motherboard, cables, power supply, and everything else that makes up the computer? Probably not. Hand-in-hand with protection, a computer case also doubles as a way to hide all those parts of the computer that nobody really wants to see each time they look in that direction.

Another good reason to use a case is to keep the computer cool. Proper airflow over the internal components is one more benefit to using a computer case. While the case has special vents to allow some of the fan air to escape, the rest of it can be used to cool down the hardware, which would otherwise get pretty hot and possibly overheat to the point of malfunction.

Keeping noisy computer parts, like the fans, in a closed space within the computer case is one way to reduce the noise they make.

The structure of the computer case is also important. The different parts can fit together and become easily accessible to the user by being compacted in a case to hold it all together. For example, USB ports and the power button are easily accessible, and the disc drive can be opened at any time.

Computer Case Description

The computer case itself can be constructed from any material that still allows the internal devices to be supported. This is usually steel, plastic, or aluminum but might instead be wood, glass, or styrofoam.

Most computer cases are rectangular and black. Case modding is the term used to describe the styling of a case to personalize it with things like custom internal lighting, paint, or a liquid cooling system.

The front of the computer case contains a power button and sometimes a reset button. Small LED lights are also typical, representing the current power status, hard drive activity, and sometimes other internal processes. These buttons and lights connect directly to the motherboard, which is secured to the inside of the case.

Cases often contain multiple 5.25-inch and 3.5-inch expansion bays for optical drives, floppy disk drives, hard drives, and other media drives. These expansion bays are located at the front of the case so that, for example, the DVD drive can be easily reached by the user when in use.

At least one side of the case, perhaps both, slide or swing open to allow access to the internal components. See our guide on opening a computer case for instructions, or see what the inside of a PC looks like.

The rear of the computer case contains small openings to fit the connectors contained on the motherboard, which is mounted inside. The power supply is also mounted just inside the back of the case, and a large opening allows for the connection of the power cord and use of the built-in fan. Fans or other cooling devices may be attached to any and all sides of the case.

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