The most important piece of pc hardware is the central processing unit, or CPU. This chip makes digital instructions for all other hardware to run.
RAM — or random access memory — temporarily stores software applications and user data. Most desktop PC RAM comes on a card called a DIMM that plugs into the motherboard.
Processor
The central processing unit, or CPU, acts as the brain of your computer. It processes data and tells other hardware like your monitor, hard drive, and graphics card what to do.
A CPU contains circuitry that performs arithmetical, logic, and input/output functions. It also includes a floating point unit, which manipulates numbers more quickly than basic microprocessor circuitry can, and cache memory that stores instructions and data locally.
Intel’s i7 processor, for example, has six cores and clocks up to 3.7 gigahertz. It also has L1 and L2 cache, which allow it to store data locally and access it faster than would be possible by retrieving it from random-access memory.
Memory
Unless you have an external hard drive, your computer stores all of its data and instructions inside of internal memory. This is called random access memory (RAM).
RAM is volatile, which means that it loses its data when the computer shuts down. It is a set of chips packaged together on a little card that plugs into the motherboard (called a DIMM).
For maximum performance, identical sets of RAM should be installed in matching slots or “banks” on a motherboard. The latest motherboards feature so-called quad-channel RAM, which performs at its best when fitted with quartets of DIMMs. In addition, there is a piece of hardware called cache, which is fast memory built into the processor itself to reduce the need for it to transfer data in and out of standard RAM.
Hard Drive
Hard drives are non-volatile storage devices that store your data and operating system. They hold your documents, pictures, music, videos and programs and are the main method of saving files between computers.
The HDD contains an array of rigid rapidly rotating platters coated with magnetic material, along with a set of arms that read and write data to the platters. The head flies above the platters at a very close distance, changing the magnetism of each tiny portion of the platter that represents a data bit (1 or 0). A flexible ribbon cable connects the actuator assembly to the drive’s logic board to manage reading and writing operations.
Graphics Card
The graphics card takes instructions from the CPU and transforms them into images on your screen. It is capable of rendering tens of thousands of pixels every second, allowing a computer to display uber-realistic images.
Graphics cards can be integrated (built into the motherboard) or discrete. Discrete cards are standalone pieces of hardware that can be removed from the system, while integrated ones live on your motherboard and cannot be changed or upgraded.
They work by transferring data between the GPU and video memory, which is separate from your normal RAM. To see your video memory capacity, open System Information and look under the Components section.
Sound Card
A sound card is a component that translates digital audio signals into analog ones. It has an input connector for a microphone or auxiliary device and output ports for speakers and headphones. It also has an internal digital-to-analog converter and an analog-to-digital converter, and it uses dedicated chips to lessen the burden on the computer’s CPU.
It may have a MIDI port, which allows it to work with a keyboard or other MIDI device. It may also have additional ports for a joystick or microphone.
It comes with software that allows the user to control its functionality. Some cards come with their own proprietary drivers, while others rely on universal middleware that’s loaded by the operating system.
Motherboard
The motherboard is the hardware circuit board that connects all of the other components of your computer. It houses essential circuits, chips and sockets that determine the performance, expandability and compatibility of your system.
Motherboards contain sockets for installing your CPU (the computer’s mechanical “brain”), as well as RAM memory slots for adding sticks of volatile memory that store and retrieve data quickly. They also include PCIe slots for expansion cards that provide additional functionality, such as audio and video.
A cooling fan on the motherboard draws heat away from the CPU and other components, preventing them from overheating. All motherboards have a power connector and a CMOS battery for backup power.