The CPU (Central Processing Unit) is the part of a computer system that is commonly referred to as the "brains" of a computer. TheCPU is also known as the processor or microprocessor.
The CPU fan blows the heat generated from the components away, and actively cools the processor by bringing in cooler air before the heat damages the computer components.
RAM also called random access memory, a type of computer memory that can be accessed randomly; that is, any byte of memory can be accessed without touching the bytes. RAM is the most common type of memory found in computers and other devices, such as printers.
Hard drive is a data storage device used for storing and retrieving digital information using one or more rapidly rotating disks (platters) coated with magnetic material.
A power supply is an internal hardware component that supplies components in a computer with power. The power supply converts a 110-115 or 220-230 volt alternating current into a steady low-voltage direct current usable by the computer.