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PC COMPONENTS
System Unit Cases
This is the cabinet that holds the main components of
a computer. It includes a plastic front panel for
aesthetic purpose. PC have been packaged in a
number of different case designs. Each design offer
characteristics that adapt to the system to different
environment
The characteristics for case design include the
following
 Ventilation characteristics
 Total drive capacity
 Foot print (amount of desk space the case takes up)
 Portability
 Mounting methods for the printed a circuit board
PC case designs fall into three basic styles
Desktop:- cases style in which the desktop unit sit
horizontally on a desktop
2. Towers:- cases are designed to sit vertically on the
floor to provide more usable workspace on the
desktop. Mini tower & mid towers are short towers
designed to take up less vertical space.
3. Portables:- To free users from their desks. These
units package the system unit, input units and
output unit into a single lightweight package that
user can carry.
1.
INSIDE THE SYSTEM UNIT
The system unit is the basic of any PC system
arrangement. The components inside the system unit
can be divided into 5 distinct sub units.
1.
2.
3.
4.
5.
Switching power supply
Disk drives
System board
Signal cables
Options adapter card
POWER SUPPLY
 The component in the system that converts the AC
voltage from the commercial power outlet to the DC
voltage required by the computer circuitry.
 It delivers power to the system board and its
expansion slot.
 The form factor (shape& dimension) of the Power
supply must much that of the case that it is supposed
to go into and the mother board.
Figure 1: Power Supply
SYSTEM BOARDS
 It obtains the circuitry that determine the computing
power and speed of the entire system it is also
referred to as motherboard and planer boards.
 Types – BTX – Balanced Technology extended
ATX – Advanced Technology Extended
The Differences Between BTX and ATX
 Slightly larger than ATX
 Smaller than BTX
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 divide the PC into zones,
hence always the CPU
appear in the same zone
 -designed to place the
CPU towards the front of
the case for better coiling
is more efficient cooling
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 PC pulls air in through to
back into the computer
and pushes it directly
into microprocessor
Figure 2: Motherboard
Tutorial Questions
What are the differences between BTX and ATX
motherboard?
Hard disk drives.
 These are the mainstay of mass data storage in a PC
 Its capacity is measured in the following units
-MB
-KB
-GB
-TB
Types of Hard disk
1.
2.
3.
4.
5.
ATA (AT Attachment)
SCSI (Small Computer System Interface)
Fire wire
RAID (Redundant Array of inexpensive Disk)
Fiber channel
ATA
PATA (Parallel ATA)
 Uses 40-or-80 pins wide
ribbon cable to transfer
multiple bits
simultaneously.
 Requires 5volts for
transmission.
 Cable limit is 18 inches
 When two disk are
connected together,
share the bandwidth
Example: IDE Hard Disk




SATA ( Serial ATA)
Serial data transfer (I bit
at a time)
7 –pin data connection
Cable limit is I meter
Only
Only one disk drive per
serial so they do not have
to share data bandwidth