Components of the Computer System Unit

Components of the System Unit 

  • Internal Power Supply (SMPS) 
  • Exhaust Fan 
  • Speaker 
  • Motherboard 
  • Storage Systems 
  • Microprocessor
Components of the Computer System Unit

Storage Device/Media 

  • Data needs to be stored for later use on storage media. 
  • The two types of storage media are: 
    • Primary storage media 
    • Secondary storage media

Primary storage media

  • It is the internal storage area of the machine. 
  • Random Access Memory (RAM) 
  • This is the memory that the computer uses for storing the programs and their data while working on them. 
  • RAM has the following characteristics: 
    • Data within the RAM can be read or modified, i.e. you can either read from the RAM or write onto it. Hence it is called read/write memory 
Random Access Memory (RAM)

Secondary storage media 

  • Compact Disk (CD ROM) 
  • Floppy Disk 
  • Cartridge Tape 
  • Magneto-Optical Disk 
  • USB drive / Pen Drive 
  • Memory Stick 
  • Hard Disk

SMPS (Switch Mode Power Supply) 

  • The system draws power from AC mains through a power protection device. 
  • This power is not directly supplied to the internal components , instead one of the components called Internal Power Supply. 
  • Otherwise known as Switched Mode Power Supply.
  • It can convert the AC input into DC output of 5 & 12 volts. 

Exhaust Fan 

  • The SMPS has a small fan, called exhaust fan, attached to it. 
  • It can rotate as long as the system switched on. 
  • Main function is – cool the SMPS Unit 


  • The system unit has also a small audio speaker attached to it. 
  • It is connected with the Motherboard.  It can create a beep sound to indicate everything is working satisfactory. 
  • Also used to entertainment programs to produced sound effects. 


  • When you open the system unit, a large board containing a number of tiny electronic circuits called Motherboard. 
  • All PC peripheral devices are connected with the Motherboard. 


  • The microprocessor consists of ALU Unit, Control Unit, Memory unit 
  • It can move data from one memory location to another 
  • The capacity of Microprocessor is measured in the term of the number of bits it can send or receive & the number of bits it can process internally. 
  • Ex – 8088 --- 8 / 16 bit processor 
  • 80286 – 16 / 16 bit processor 
  • Manufacture company – Intel , Motorola 
  • Pentium is a 32 bit processor 
  • Pentium IV is a 32 bit processor with 64 data path.