Definition - What does System Unit mean?
A system unit is the part of a computer that houses the primary devices that perform operations and produce results for complex calculations. It includes the motherboard, CPU, RAM and other components, as well as the case in which these devices are housed. This unit performs the majority of the functions that a computer is required to do.
The term system unit is generally used to differentiate between the computer itself and its peripheral devices, such as the keyboard, mouse and monitor.
A system unit is also known as a chassis or a tower in layman's terms.
Techopedia explains System Unit
The system unit holds the system devices that perform calculations as requested from the input device, which can range from a microprocessor to a capacitor or system clock.
Every system device has its own function. The system unit includes the electronic equipment that interacts simultaneously in order to perform calculations and transfer the results to the corresponding input and output devices.