Motherboards
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Motherboards
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The Motherboard or System Board is the spine of the
computer.
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Purpose: It is the component that connects all of the other
components of a PC together.
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Every piece of hardware, directly or indirectly plugs into the
motherboard.
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All data and commands flow from one place to another by
using buses known as traces, which are embedded in the
motherboard.
Motherboards
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
Modern motherboards are officially printed circuit boards
(PCBs) and come in multiple layers.

You can see some of the traces on the boards, but every
motherboard is two or more layers thick.
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The fact that a motherboard is multi layered, makes it
possible to have smaller motherboards, and thicker thus
stronger.

When the motherboard is small, the distances are shorter,
therefore data flow is faster.
Motherboards
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All motherboards are defined by 3 interrelated
characteristics:
1.
2.
3.
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Components
Form Factors
Chipset
A good technician should be able to make a
recommendation to a client when choosing a
motherboard, according to the above 3 characteristics.
Motherboards
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Form Factor: determines the layout and dimensions of a
motherboard, and the locations of components and ports.
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Chipset: defines the type of CPU and RAM required for the
motherboard, and determines the built-in devices supported
by the motherboard, including the expansion slots.
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Built-In Components: determine the core functionality of
the system
Components
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CPU Socket
RAM Slots
Chipset
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Northbridge
Southbridge
Super I/O
ROM
CMOS Battery
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AGP
PCI-e
Expansion Slots
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Video Card Slot
PCI Cards
Power Connectors
IDE Connectors
SATA Connectors
Peripheral Connectors
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Form Factors
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The Form Factor determines the layout and dimensions
of a motherboard.

All of the motherboards come in a basic rectangular
shape, but vary in the size and the layout of built-in
components.
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Mainly, a form factor relates to the case and the power
supply of a PC. The case must be designed in a way to
fit the motherboard, and the power supply and the
motherboard need matching connectors.
Form Factors
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
Motherboards come in standard form factors. We will
focus on the following form factors:
– AT & Baby AT
– LPX & NLX
– ATX
– BTX
… and variants of these

Most PC cases are only designed to work with one form
factor.
Form Factors - AT
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AT – Advanced Technology
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The old style motherboards follow a form factor called AT,
also known as Full AT. At is now obsolete.

The AT form factor invented by IBM in the early 1980s. It
was the predominant form factor through the mid 1990s.
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The processor, memory and expansion slots are all in line
with each other.
Form Factors - AT
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At had a relative large keyboard port.
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The problem with AT was the lack of external ports. In
fact, at that time, the only devices plugged into an
average PC were a monitor and a keyboard.

Over the years, AT had to be replaced because the
number of devices plugged into the back of the PC has
grown.

AT motherboards catered for just a monitor and a
keyboard. An average PC today includes keyboard and
mouse, printer, speakers, monitor and USB devices.
Form Factors - AT
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
As technology improved and the PC flourished(‫)تطورت‬, the
demand for smaller PCs increased.

Manufacturers created a smaller motherboard by placing
the same components in a smaller area - Baby AT.
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The problem with the Baby AT was the placing of the
components, which resulted in limited expandability and
overheating
Form Factors - AT
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Form Factors - AT
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Form Factors – LPX & NLX
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Added components created demand for a new standard
form factor.
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One form factor that enjoyed a degree of success was
the slimline factor. The first was known as the LPX (Low
Profile Extended). It was then replaced by the NLX.
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In this type of form factor, you have a small riser in the
center with cards attaching to it horizontally. The aim is
to use the space optimally.
Form Factors - LPX
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Form Factors - NLX
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Form Factors - NLX
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Form Factors - ATX
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ATX – Advanced Technology Extended
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There continued to be a tremendous demand for a new
form factor – a form factor that had more standard
connectors, but at the same time was flexible enough for
possible changes in technology.
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This led to the creation of the ATX form factor in 1995.
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ATX got to a slow start but by around 1998, ATX took
over AT to become the most common form factor used
today.
Form Factors - ATX
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The ATX form factor includes many improvements over
AT.
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The position of the power supply enables better air
movement.
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The CPU and RAM are placed to enable easier access.
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Other improvements, such as the placement of the RAM
closer to the Northbridge and CPU, than on AT boards,
which results in better performance.

New smaller ports for the motherboard and keyboard
were introduced, known as PS/2.
Form Factors - ATX
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ATX motherboards use a feature called soft power. This
means they can use soft power to turn the PC on and off.
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Instead of the thick power cord used in AT systems, an
ATX power switch is a pair of small wires leading to the
motherboard.
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Later version of ATX are the microATX and the FlexATX,
the latter being the smallest ATX motherboard.
Form Factors - ATX
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Form Factors - ATX
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Form Factors - BTX
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BTX – Balanced Technology eXtended.
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Even though ATX took care of ventilation(‫)تهوية‬, heat
remained a problem because of faster CPUs and
powerful graphics cards. Therefore BTX was introduced.
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So the aim of BTX is to create the coolest new form factor
today, and any change in the design was done
specifically to improve cooling, by managing heat by one
single air flow!
Form Factors - BTX
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These are the main changes in the design of the BTX:
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The I/O Ports and the expansion slots have changed sides
on the actual board.
CPU moved to the front of the motherboard to get cool air
from the front of the case.
A new fan & heatsink system was introduced, known as the
‘thermal unit’.
Finally, the thermal unit blows the air directly outside the
case, and not in the case itself, like the fan in the ATX.
BTX comes in 3 versions: BTX, micro BTX and picoBTX.
Form Factors - BTX
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Form Factors - BTX
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Form Factors – ATX vs BTX
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Chipset
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Every motherboard has a chipset.
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The chipset defines the motherboard in many ways,
determining which processor type and memory type it can
use, and what sort of internal and external devices the
motherboard will support.
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Chipsets vary in feature, performance and stability, so they
factor hugely in the purchase or recommendation of a
particular motherboard.
Typical Chipset Diagram
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Chipset
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Because the chipset facilitates communications between
the CPU and other devices in the system.
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The chipset component chips are relatively centrally located
on the motherboard.
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Most modern chipsets are composed of two primary chips:
- Northbridge chip
- Southbridge chip
Chipset – Northbridge & Southbridge
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The Northbridge chip is responsible for AGP
communications and memory communications.
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Since Northbridge chips deal with memory, they do a lot
and thus get pretty hot, so they get their own heat sinks.
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The Southbridge chip is responsible for onboard
peripherals such as audio, storage drives, network and
expansion buses. Most Southbridge chips do not include a
heatsink.
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So the Northbridge is responsible for high-speed
motherboard components, while the Southbridge is
responsible for lower speed components.
Chipset – Super I/O
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Old technologies such as ISA slots, floppy drives,
infrared, parallel ports, serial ports and PS/2 were
supported by the Southbridge.
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Modern chipsets hardly support these devices anymore,
so manufacturers created a third chip – Super I/O to
handle such devices.
Chipset
including
Super I/O
Northbridge,
Southbridge,
&Super I/O
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Chipset
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Every device on the PC needs BIOS support so that the
CPU knows how to use that device properly.
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The chipset is no exception.
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The System ROM chip provides part of the BIOS for the
chipset.
The chipset still needs support for the rest of the things it
can do.
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This is done by using Software Drivers. You have to load
the proper drivers for the specific OS.
Chipset - Manufacturers
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Both INTEL and AMD make chipsets. They lead the
market, though they have some serious competition, like
VIA Technologies and NVIDIA Corporation.
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Chipset manufacturers do not always use the terminology
of Northbridge and Southbridge. They create their own chip
names.
For example, while AMD use the terms Northbridge and
Southbridge, INTEL uses the terms Memory Controller
Hub and I/O Controller Hub, respectively.
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SATA Connector
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Serial ATA (SATA) is an IDE standard for connecting devices
like optical drives and hard drives to the motherboard.
SATA cables are long, thin, 7-pin cables. One end plugs into a
port on the motherboard, usually labeled SATA, and the other
into the back of a storage device like a hard drive
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Choosing the Motherboard and Case
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Choosing a Motherboard and case can prove quite a
challenge for a technician:
1.
First, determine what motherboard you need.
2.
Second, make sure the form factor of the motherboard
matches with the case.
3.
Third, use the motherboard manual to find out what
features does the motherboard provide and configuration
details
4.
Fourth, select the case that matches space needs and the
motherboard’s form factor.
Choosing the Motherboard and Case
1. First, determine what motherboard you need.
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Are the motherboard and CPU compatible with each other?
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Possibly, when you buy a motherboard and a CPU, choose
a motherboards that works with higher speeds than the
CPU, so that you can upgrade later without changing the
motherboard.
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Figure out how much RAM is supported by the
motherboard, and the number of memory slots in the
motherboard.
Choosing the Motherboard and Case
2. Second, make sure the form factor of the motherboard
matches with the case.
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
Form factors determine the size and layout of the
motherboard, so different form factors fit within different
cases.
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Don’t try to put a regular ATX motherboard intro a microATX
case!
Choosing the Motherboard and Case
3. Third, use the motherboard manual to find out what
features does the motherboard provide and configuration
details
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All motherboards come with a technical manual. The
manual contains all of the critical information about the
motherboard.
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One typical instance when we need the manual, is when we
need to find out certain CMOS settings and how to deal with
them.
Choosing the Motherboard and Case
4. Fourth, select the case that matches space needs and
the motherboard’s form factor.
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Cases come in 6 basic sizes: slimline, desktop, mini-tower,
mid-tower, tower, and cube.
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Cases come with or without the following features:
• Removable face
• Detachable motherboard mount
• Front-mounted ports and power supply
Troubleshooting Motherboards
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Motherboards fail, not often but both motherboards and
their components can die form many causes: time, dust
or simply slight manufacturing defects.

Installing cards, electrostatic discharge, flexing the
motherboard one time too many when swapping RAM or
drives – any of these factors can cause a motherboard to
fail.
Troubleshooting Motherboards
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Motherboard failures commonly fall into three types:
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Catastrophic Failure – The PC won’t boot.
Component Failure – Intermittent problems mostly
Ethereal Failure – PC reboots itself & blue screens
Troubleshooting Motherboards
Catastrophic Failure
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The PC just won’t boot.
Happens with brand new systems (burn-in failure) due to
manufacturing defect and systems that get a shock of
ESD.
Burn-In-Failure usually happens within the first 30 days
due to a motherboard problem.
Troubleshooting Motherboards
Component Failure
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Intermittent problems
Happens because of bad connections between a device
and the motherboard.
The problem here is actually in the motherboard itself.
Usually if you replace the device, you will still have the
same problem.
Troubleshooting Motherboards
Ethereal Failure
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PC reboots itself & Blue Screens
Staff doesn’t work all the time.
The causes are usually the following:
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Faulty Component
Buggy Device Driver
Buggy Application Software
Slight Corruption of the Operating System
Power Supply Problems