CPU system unit

The system unit, like the one above is the case that contains all the electronic components of any computer system.
The electronic components are considered internal hardware seeing that they are inside the system unit and you cannot see when you look at the computer.
These components inside the system unit are what process the data and really makes the computer work. Internal components are as follow:
Power Supply: The power supply converts electricity into the current works for the computer. When the computer is turned on the power supply allows converted electricity to travel to other components inside the computer.
Motherboard: The motherboard is the circuit board that holds the main internal components of the computer together. On the motherboard there are three major cards; sound card that operates the sound, the video card that handles the graphics that you see on the monitor and the modem card which allows computers to communicate with each other. Also on the motherboard is the Central Processing Unit (CPU), processor or brain of the computer. The CPU controls information and tells the other components inside the computer what to do.
RAM & ROM: RAM stands for random access memory. This memory holds theinformation you are working with while the computer is turned on. Once you turn the computer off all the information that was in RAM will be gone. ROM stands for read only memory. This memory holds information that you can only read, but not erase. Information in ROM is built in and is always there even when the computer is turned off.
Disk Drives: The disk drive is the device that reads information that is on disk. Generally speaking most computers have three disk drives; hard disk drive, floppy disk drive and CD-Rom drive. However, there computers that have DVD-Rom drive. While the hard disk is hidden inside the computer the floppy and CD-Rom drives are accessible from the front of the system unit.