System Unit

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.

PARTS OF A SYTEM UNIT

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. 

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. 

• 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.

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.

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.

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.

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.

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.

• 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)

• 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)

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 InterconnectAGP – Accelerated Graphic Port

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.

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. 

CPU FAN AND HEAT SINKAn electronic device that to keep the processor cool

BASIC INPUT OUTPUT SYSTEMA 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.

NORTHBRIDGEResponsible for communications

between the CPU interface, AGP, and the memory.

SOUTHBRIDGEResponsible 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.

PCI SLOTUsed by the computer to connect to peripheral

add-on devices (LAN card, VGA card).

AGP SLOTIs 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.

PRIMARY CONNECTOR (HDD)

Used to connect the HDD to motherboard.

SECONDARY CONNECTOR (ODD)

Used to connect the ODD to motherboard.

FDD CONNECTORUsed to connect the FDD to

motherboard.

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

CAPACITORStores the electrical energy and give this energy again

to the circuit when necessary

AUDIO CODECUsed to convert digital sound waves

BACK PANELThe portion of the motherboard that allows you to connect external devices such as

your monitor, speakers, keyboard, mouse and others.