Internal Parts of a Computer

By Shawn McClain

A computer is the combination of a few basic parts.
i Computer image by Haris Rauf from

A modern computer may contain hundreds of different controllers and chips, but even the most complicated of machines can be boiled down to a few simple parts. Understanding just these parts can give you an excellent idea of how a computer operates, and this knowledge can allow you to make better purchasing decisions the next time you are shopping for a system.


The motherboard is the main circuit board that all other computer components either sit in or are connected to. The motherboard type will determine what kind of processor and memory chips can be installed on the computer, along with what kind of external connections, such as USB, are natively supported. Some motherboards also will include onboard video and sound, removing the need for expansion cards.


The processor is probably the most important internal part of your computer, as it is where almost all of the computations required to run the computer take place. The processor sits inside of a small socket near the middle of the motherboard, and on top of executing code for your programs, it also controls how the other computer components communicate and operate. The processor's power is measured in megahertz, and more recently gigahertz, with a higher number representing more processing power.


When the processor needs information for a particular program or task, it first loads that data into random access memory. or RAM. RAM is short-term memory, meaning that it gets wiped out every time the computer loses power or gets reset, but its speed of access makes it ideal for being the computer's primary storage.

Hard Drive

If RAM is one side of the computer's storage solution, the hard drive is the other. Instead of being fast-accessed, short-term storage, hard drives are slowly accessed, long-term storage. Any file or piece of information that may be needed more than once is stored on the hard drive. When the processor needs a file or set of files to run a program, it copies them from the hard drive and loads those copies into RAM. Hard drive capacities are measured in gigabytes, or sometimes terabytes, with the larger numbers representing more capacity.

Video Card

While some older motherboards have built-in video, most modern systems require a separate video card to output graphics. The pure computational power required to render modern graphics require a separate processor and cooling unit that is housed on this video card. The card itself is connected to the motherboard using an expansion slot.

Expansion Slots

These slots sit near the back of the computer and allow you to install devices to upgrade the system. These devices, which look like cards that slide into these slots, can be used for audio, video, network capabilities, additional USB connections and more. Some slots, like an AGP slot, are used exclusively for video cards, but most of the slots on modern systems are generic PCI-X slots that are used for all cards.

Power Supply

The power supply is generally located in one corner of the back side of your computer case. On the side that faces out of the computer it has a single plug for your power cable and openings for the cooling fan. On the side that faces the inside of the system it has a set of power wires that you use to supply power to all the computer's internal devices. Some devices, like RAM or small expansion cards, get enough power through the motherboard so they don't need a direct connection to the power supply, but most other device do need to be plugged into one of these wires to operate.