It powers all of your computer's individual components and the interface between your computer and the wall socket into which you plug your computer.
PSU - POWER SUPPLY UNIT
It keeps the inside of your case at a safe temperature.
COOLING SYSTEM
It provides more "workspace" to increase your computer's performance.
RAM /MEMORY
The chipset which contains the basic program and system configuration of the computer.
BIOS
It is necessary for holding/storing and cooling your components
CASE OR CHASSIS
serves as an interface between all of your computer's components and the processor.
MOTHERBOARD
It connects the peripherals to your system unit.
I/O CONNECTORS
It used to render images on your computer.
GRAPHICS CARD
It stores data.
HARD DISK DRIVE