According to the Computer Science Department at the University of West Florida, the components of a computer system unit include the processor, memory module, ports, cards and connectors. The system unit houses those computer components that are necessary for data processing.
The majority of the components of a computer system are located on the motherboard inside the computer's chassis. The processor, or CPU, handles the calculations required to run a computer program and serves as a system coordinator, directing all traffic running through the system and providing instructions to all of the rest of the components. The memory module stores the system's instructions, making them readily available to the processor to make use of in an orderly fashion. These instructions are provided by various software applications such as the operating system or a word processor.
The ports and connectors handle the input and output functions of the computer, sending and receiving data to the system's various peripherals such as the keyboard, mouse or printer. Cards are add-ons that plug into the motherboard. These include anything from graphics cards that process video and outputs the results to a monitor to RAID cards that are used to control multiple hard drives for greater speed, efficiency or to allow for data redundancy.