Parts of the System Unit.

There are three major components of computer system: The Software, Peopleware and Hardware. If you want to be skillfull in operating a computer, you need to memorize the parts of a system unit and be familiar with their roles in your computer. Also computer hardware types, specification and their current price in the market is important for these will give you more options and helps you and others to make good decisions in buying a new one.

Let us review the parts of the system unit.
Parts of system unit
View more presentations from kapitanbasa.

Parts of a System Unit

MOTHERBOARD is also called the "System Board," it is the main printed circuit board in an electronic device, which contains sockets or slots that accept additional boards.

The CPU, or the Central Processing Unit, is the brain of the computer and one of the most important chip in the computer.New CPUs are small and square and contain multiple metallic connectors or pins on the underside. The CPU is inserted directly into a CPU socket, pin side down, on the motherboard. Each motherboard will support only a specific type or range of CPU so checking the motherboard manufacturer's specifications before attempting to replace or upgrade a CPU is important. It is also necessary toattach heat sink and small fan directly on top of the CPU to help dissipate heat.
The CPU resides on the CPU socket. There are two types of CPU holder which you may encounter nowadays:
A. LGA - Land Grid Array (LGA). This socket has no holes, but instead pins are located from the CPU socket that makes contact with points on the underside of the CPU.
B. PGA - Short for pin grid array, a processor sockets that use a pin grid array (PGA) where pins on the underside of the processor connect to holes in the processor socket.


Internal Storage device are installed inside the system unit. This is the computer's main storage device used to store all data on the computer permanently. Commonly, hard drives are permanently place in an internal drive bay at the front of the system case and are connected with either ATA, SCSI, or a SATA cable and power cable. Some Hard drives nowadays are portable which use USB ports and USB cable for connection.

Types of Internal Storage Device commonly used in System Unit: 

Hard Disk Drive (HDD) is also known as hard drive. HDD or Hard Disk Drive use magnetic storage disk inside to store data.


RANDOM ACCESS MEMORY: The personal computer memory module also known as Random Access Memory (RAM) is a piece of hardware that allows stored data to be accessed randomly. Its main function is to store the data temporarily.

Note: Desktop Memory requires Non-ECC unbuffered Memory module or usually called Value RAM.
Server computer uses ECC Registered Memory and it cannot be installed in Personal Desktop computers.  

ECC (Error Correcting Code) is an additional features that can be found in Server memory  which allows the motherboard to detect and correct one bit errors.

The types of RAM are the following:

1. DIP - Dual Inline Package. This type of memory was used by old motherboard. 

2. SIMM - Single Inline Memory Module. After the Dual Inline Package, designers soldered the DIP into a circuit board so it will be easily installed. 

3. RIMM - This is a trademark of RAMBUS which is similar to a DIMM package but uses different pin settings. 

4. SODIMM - Small Outline Dual Inline Memory Module. This type of memory is used in laptop or mini laptop

5. DIMM - Dual Inline Memory Module


The types of Dual Inline Memory Module (DIMM) for desktop computers are the following:

1. SDRAM has 168 pins with 2 notches
2. DDR has 184 pins with 1 notch
3. DDR2 - 240 pins with 1 notch
4. DDR3 - 240 pins with 1 notch

You cannot install DDR3 memory on motherboards that will require DDR or DDR2 memory only. 
  • SDRAM, synchronous dynamic random access memory
  • DDR SDRAM, double-data-rate synchronous dynamic random access memory
  • R DRAM, rambus dynamic random access memory
  • DDR2 SDRAM, double-data-rate 2 synchronous dynamic random access memory
  • DDR3 SDRAM, double-data-rate 3 synchronous dynamic random access memory
The DDR are largely used now as they are faster, and demand less power than SDRAM

VIDEO CARD is commonly known as graphics accelerator card, display adapter, or graphics card. This is a hardware component whose main function is to generate and display the output images to a computer monitor.

Here are the common features of video card.

  • Video Card GPU (Graphics Processing Unit) is a new feature of today’s video card where that render possible graphics rendering and it is the efficiency of the microchips that will determine the graphic acceleration.
  • Video RAM -(VRAM) is attached at the graphic card and its main feature is the capacity of dual-porting. This means it can simultaneously be written and read. It gives the advantage of calculating and send screen images to the monitor and start reading new images at the same time without bumping.
  • Svideo - Separate Video or Super Video is the technology used to connect computer, Television, game console, DVD player etc.To use S-Video, the device sending the signals must support S-Video output or port and the device receiving the signals must have an S-Video input jack. Then you need a special S-Video cable to connect the two devices.
  • DVI - Digital Visual Interface is used for digital devices like a LCD projector and new LCD monitors with the DVI connector. DVI brings more higher resolution than VGA technology.
  • VGA -Video Graphics Array, a graphics display system for PCs which uses analog signals rather than digital signals. All PC’s today support VGA.

SOUND CARD is also called as audio card adapter. This is a computer expansion card used for the input and output of audio signals from a computer using a specific computer programs. New motherboard comes with built in audio adapter.

MODEM comes from two words meaning modulator of analog carrier signal to encode digital information, and also demodulatorof a carrier signal to decode the transmitted information. Because computers made connections thru telephone lines which uses analog data, data coming from computers which is considered digital must be converted with the use of MODEM.

FLOPPY DISK DRIVEor FDD for short was the primary means of saving and retrieving data to a computer. Basically, a floppy disk drive reads and writes data to a small, circular piece of metal-coated plastic similar to audio cassette tape.

CD-ROM/DVD-ROM DRIVE uses photo diodes to detect reflecting lights on optic discs and uses a laser to read or write data. Commonly, it uses the same cables as hard drives to connect to the motherboard.
Optical Drive (CD ROM Drive)

DVD RW DRIVE is used to read data on CDs and DVDs, create your own CD DVD movies that can played on your TV CD DVD player or makea system backups or transferring data from one computer to another.


  1. SWITCH is a local area networking device which serves as a central connection for all network equipment and handles a data type known as frames. Frames carry your data. When a frame is received, it is amplified and then transmitted on to the port of the destination PC. 
  2. ROUTER role is to route packets to other networks until that packet ultimately reaches its destination. One of the key features of a packet is that it not only contains data, but the destination address of where it's going.Commonly, a router is connected to at least two networks, two LANs or WANs. Router could be wired or wireless. Network Interface Card is commonly known as LAN card. This is an expansion board insert into motherboard PCI slot so the computer can be connected to a network. NIC could be wireless which popularly known as wireless LAN card.
  3. NETWORK CABLE A common network cable ismade up of UTP (Unshielded Twisted Pair) or STP, (Shielded Twisted Pair) crimped with
  4. RJ45 (Registered Jack).Network cable is used to connect computers together. RJ 45This is a standard physical Network Interface used for connecting telecommunications equipment commonly, a computer networking equipment.
Video Card Adapter is commonly known as graphics accelerator card, display adapter, or graphics card. This is a hardware component whose main function is to generate and display the output images to a computer monitor.

There are many video card adapter manufacturer but there are only two manufacturer of GPU or the Graphical Processing Unit.

Graphical Processing Unit (GPU) or the video processor is the chipset where the processing of data for graphic occurred. The GPU of any video adapter will tell the card’s performance levels.

The Two common GPU manufacturer are 

NVIDIA - www.nvidia.com


AMD - www.amd.com


Examples of Video Card Adapter Manufacturer