Difference Wiki

System Unit vs. CPU

System Unit of a computer is also called computer case, computer tower or desktop. It is the unit that possesses all the main internal things inside attached each other forming a whole system. It is also known as computer chassis. It is a hardware frame inside which all the systematic electrical units collectively work, Whereas CPU is the central processing unit of a computer system. It is the brain of the computer and is responsible for all the logic works, assigns the tasks and assures the processing of information in the form of conclusion or output.

Key Differences

CPU is the Central Processing Unit which is responsible for all the functions performed by a computer system.
System Unit is the hardware case inside which all the internal electrical working units resides and work together collectively.
System Unit itself is not functional, but all the units perform their tasks and functions residing inside it.
Harlon Moss
Mar 11, 2017
CPU is the brain of the computer. Logical decision making, task assigning and data processing is done by CPU.
System Unit provides a common working environment for the interior components such as a motherboard, processors, hard disk, RAM,
Janet White
Mar 11, 2017

Comparison Chart


System Unit is the hardware based aluminum chase, inside which all the electrical components and other computer processors reside and work. It is also called computer tower, computer chassis and computer tower.
CPU stands for the Central Processing Unit. It is responsible for processing the input provided and provides the output as a conclusion. All the logical actions are performed under CPU’s instruction. It is referred as the brain of Computer.


Ports, hard disk, RAM, motherboard, processors, BIOS, Optical Drive, Connectors, Graphic Card, and Power Supply.
CPU has two basic components. 1) ALU and 2) CU. ALU is the Arithmetic logical unit, and CU is the Control unit.


The basic function of a system unit is that it holds all the interior of the computer residing in it together. Enables the processors and another electrical unit to work collectively in a common hardware environment.
The main function of the CPU is to process the data that is provided as input to the computer and provides the information after the conclusion as the output. Every single function performed by the computer is done via instructions of the processors.

System Unit and CPU Definitions


The central processing unit, that part of the electronic circuitry of a computer in which the arithmetic and logical operations are performed on input data, which are thereby converted to output data; it is usually located on the mainboard, or motherboard, of a computer. The CPU and the memory form the central part of a computer to which the peripherals are attached. Most personal computers as of 1998 had only one CPU, but some computers may have more than one CPU.


(computer science) the part of a computer (a microprocessor chip) that does most of the data processing; the CPU and the memory form the central part of a computer to which the peripherals are attached

What is System Unit?

System Unit is the hardware component of the computer system. It varies in size and possesses different size according to specific computer type and its demand for work. System Unit is also called the system chase, computer case, computer tower, computer desktop, computer chassis, etc. It is the main hardware component in which all the interiors of the computer system resides and work collectively. These interiors include the optical drive, hardware, RAM, power supply, BIOS, motherboard, processors, fans, cables, ports for the attachment of peripheral devices such as mouse and keyboard, graphic card, expansion slots and even the CPU is also present inside the system unit. System unit as its name states well, it is not a functional unit itself, but it provides the environment to all the other functional units and interiors to collaborate and work collectively in a commonly attached hardware chase. It is usually made up of aluminum or sometimes metal. It varies in shape and size according to the requirements of the computer.

What is CPU?

CPU is the Central Processor Unit of the computer system. It is the main component of the system. It is referred as the brain of the computer because it is responsible for all the logical activities and tasks that are performed by a computer system. The CPU is responsible for providing all the answers and queries inserted in a computer system. The data is given as input to the computer system; it is the CPU that manipulates the data and process it changes it to useful information and provides the conclusion as output to the user. CPU assigns the tasks and make other units of the system to work and perform. CPU has two main components which deal with their specific field of tasks. The two components of CPU are ALU (Arithmetic Logical Unit) and CU (Control Unit). ALU is responsible for all the mathematical based task and logical queries. This portion of the CPU deals with the data input. ALU process the given information and generates the logically supported results of the information, Whereas the Control Unit (CU) of the CPU controls all the instructions and task assigning work. It coordinates between all the hardware and software components of the computer system and works as a connector or bridge between them.

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