When many people think of a computer, they think of the hard drive tower, monitor, keyboard, and mouse together, as one unit. Each of these components is necessary to make full use of the computer, but individuals who already have many of these components can choose to save money by purchasing a barebone computer. This is a machine that includes only the parts that are absolutely necessary for a computer to operate.
Keyboards and mice allow a user to send commands to a computer, and a monitor allows a user to see a computer's output. The core functionality of a computer, however, lies within its central processing unit (CPU) — typically a chip that can perform millions of calculations in less than a second. Everything a computer does derives from the arithmetic and logical comparisons the CPU performs. A barebone computer is designed to support this core functionality, while leaving more advanced upgrades or components that support additional functions to the users, who can add or install such things themselves.
Among the components of a barebone computer is the CPU itself, mounted in the appropriate socket of a motherboard. Every piece of hardware in the computer has to connect to the motherboard because it contains the circuitry through which the different components send signals to and from the CPU. The number and types of ports on motherboards varies from model to model, but even the most basic version will include memory slots, a port for a power source, and an interface for a hard drive.
A barebone computer includes a power source that is sufficient to support the hardware inside the machine. The power source itself connects to the motherboard, which regulates the flow of power to the different hardware components. Each piece of hardware has a different power requirement, so the source must be able to provide a sufficient amount of power to meet the sum of all these requirements. If the wattage a particular power source can provide is lower than what the hardware inside the machine requires, the computer could crash or fail to start up.
CPUs store data for different programs in the computer's temporary memory, also referred to as random access memory (RAM), which takes the form of RAM sticks connected to a motherboard's memory slots. The more RAM a computer has, the more efficiently the CPU will be able to operate. The amount of RAM a computer can have is limited by the number of memory slots on a motherboard. A barebone computer that was built to have the lowest price will likely only include the number of slots, and corresponding memory sticks, that are necessary to run the user's intended operating system.
The last critical component of a barebone computer is a hard drive. These store the computer's operating system and user files in a long-term format, rather than the short-term format of RAM. Some barebone computers come with an operating system pre-installed, but some users choose to buy a machine with a blank hard drive. This allows them to save money on their purchase by not paying the additional cost of an operating system. Users who choose to buy a blank drive must have their own installation media to put an operating system on the computer, and will generally need to include an optical drive in their machine to read the installation media.