The system unit, or computer case, houses the main internal components of a computer including the motherboard, CPU, RAM, power supply, hard drives, and optical drives. The power supply provides power to these components by converting AC current from a wall outlet to regulated DC current and distributing it through connectors. The motherboard serves as the foundation and contains the CPU, memory slots, expansion slots and connectors that allow communication between components.

1. System Unit

2. SYSTEM UNIT
• One of the basic components of a computer
which contains all of the main parts of it.
•It houses the internal components of the
computer such us motherboard, CPU, RAM and
others.

3. PARTS OF A
SYTEM UNIT

4. POWER SUPPLY (Power Supply Unit/PSU)
• The component that supplies power to a computer.
• Most personal computers can be plugged into
standard electrical outlets. The power supply then
pulls the required amount of electricity and converts
the AC current to DC current.
• It regulates the voltage to eliminate spikes and surges
common in most electrical systems.

5. POWER SUPPLY (Power Supply Unit/PSU)
• The component that supplies power to a computer.
• Most personal computers can be plugged into
standard electrical outlets. The power supply then
pulls the required amount of electricity and converts
the AC current to DC current.
• It regulates the voltage to eliminate spikes and surges
common in most electrical systems.

6. • 20 ATX pin connector - connects the power supply to a particular
motherboard. ATX motherboards are attached with 20 or 24 pin
connectors.
• CPU connector - used to connect power supplies to motherboards
with on board computer processing units (CPUs). These are either
4 ("P4") or 8 pin connectors.
• Molex connector - the IDE connector that connects to hard drives
and CD ROM drives. Most computer power supplies include at
least one of these connectors.
• Floppy connector - 4 pin connector used to supply power to
floppy drives, card reader drives, and other similar devices.
• AUX connector - a 6 pin connector that is a necessary connection
for some computer motherboards.
• SATA connector - connectors for devices using serial advanced
technology attachment (SATA) interfaces, such as hard drives.
• PCI express connector - used to connect to PCI express video
cards, which receive power directly from the power supply rather
than from the motherboard.

7. OPTICAL DISK DRIVE (CD
or DVD ROM/ODD)
• A device that uses photo
diodes to detect reflecting
lights on optic discs.
• Uses laser to read or write
data.

8. FLOPPY DISK DRIVE
(Floppy Drive/FDD)
• A disk drive that
can read and
write to floppy disks.
• A computer disk drive
that enables a user to
save data to removable
diskettes.

9. HARD DISK DRIVE (Hard
Drive/HDD)
• Main storage device used to store all
the data permanently.
• Commonly, hard drives are
permanently paced in an internal
drive bay at the front of the system
case. But nowadays, there are
portable which use USB ports and
cables for connection.

10. INTEGRATED DRIVE
ELECTRONICS (IDE)
• Generally, it refers to the types of
cables and ports used to connect
some hard drives and optical
drives to each other and to the
motherboard.
• A standard type of connection
for storage devices in a
computer.

11. RANDOM ACCESS MEMORY (RAM)
• Personal computer memory
module.
• A piece of hardware that
allows stored data to be
accessed randomly. Its main
function is to store the data
temporarily.

12. • Often referred to as
the brain of the computer.
• Handles all instructions it
receives
from hardware and software
running on the computer.
CENTRAL PROCESSING UNIT (CPU)

13. • An electronic board or card added in
a personal computer so the
computer will have new functions.
• An expansion card is used to give a
computer additional capabilities, such
as enhanced video performance via
a graphics card.
EXPANSION CARD (Add-on or Interface Card)

14. A hard component use to generate and display
the output images to a computer monitor.
VIDEO CARD (Graphics Card/Display Adapter)
TYPES:
PCI – Peripheral Component
Interconnect
AGP – Accelerated Graphic Port

15. MOTHERBOARD
• A printed circuit board that is the
foundation of a computer, located at
the bottom of the computer case.
• It allocates power to the CPU, RAM,
and all other
computer hardware components.
Most importantly, the motherboard
allows hardware components to
communicate with one another.

17. CPU SOCKET
• Holds the CPU
• Allows the processor to be
connected to the motherboard.
MEMORY SLOT
• Allows computer memory (RAM) to be
inserted into the computer
• There may be 2 to 4 memory slots and are
what determine the type of RAM used with
the computer.

18. CPU FAN AND HEAT SINK
An electronic device that to keep the processor cool
BASIC INPUT OUTPUT SYSTEM
A chip located on all motherboards that allows you to access
and set up your computer system at the most basic level
COMPLEMENTARY METAL-OXIDE
SEMICONDUCTOR
An on-board, battery powered semiconductor chip inside
computers that stores information which ranges from the
system time and date to system hardware settings for your
computer.

19. NORTHBRIDGE
Responsible for communications between
the CPU interface, AGP, and the memory.
SOUTHBRIDGE
Responsible for the hard drive controller,
I/O controller and integrated hardware.
Integrated hardware can include the sound
card and video card if on the
motherboard, USB, PCI, IDE, BIOS, and
Ethernet.

20. PCI SLOT
Used by the computer to connect to peripheral add-
on devices (LAN card, VGA card).
AGP SLOT
Is an advanced port designed for Video cards and
3D accelerators.
ATX POWER CONNECTOR
• The standard motherboard power connector.
• The holes on the power connector are keyed to
ensure proper orientation when connecting the
ATX power connector.

21. PRIMARY CONNECTOR (HDD)
Used to connect the HDD to motherboard.
SECONDARY CONNECTOR (ODD)
Used to connect the ODD to motherboard.
FDD CONNECTOR
Used to connect the FDD to motherboard.

22. SUPER I/O (INPUT/OUTPUT)
Handles the slower and less prominent input/output devices
shown below
• FDD Controller
• Game Port
• Keyboard/Mouse
• Parallel and Serial Port
• CMOS
CAPACITOR
Stores the electrical energy and give this energy again to the
circuit when necessary
AUDIO CODEC
Used to convert digital sound waves

23. BACK PANEL
The portion of the motherboard that allows you to
connect external devices such as your monitor,
speakers, keyboard, mouse and others.