The Motherboard
Objectives
After completing this section you will:
• Understand the major components on a motherboard including the
microprocessor, chipset, math coprocessor, and expansion slots.
• Understand the basic operation of a microprocessor and what issues
must be considered when upgrading it.
• Recognize and identify the microprocessor.
• Understand the differences among the various architectures and buses.
• Recognize different expansion slots.
• Recognize an adapter’s architecture or bus.
Microprocessor Overview
• Microprocessor (or processor)
• CPU (Central Processing Unit)
• Clones – IBM compatibles
• PC – Stands for Personal Computer, another name for the
microcomputer.
 We will focus on compatibles (or non-Apple computers) because they
make up the majority of computers in use today.
 Because Intel and AMD are the microprocessors primarily used in today’s
computer industry, they are the examples covered extensively in this
material.
Microprocessor Basics
• Bit – Either a 1 or 0. All microprocessors use 1s and 0s to calculate or
interpret information.
• Byte – Eight bits grouped together, the letter A looks like 01000001 to the
processor. Each character on the keyboard appears as one byte (or eight
bits) to the CPU. Denoted by the letter B, thirty-two bytes is 32B.
• Kilobyte – Approximately 1,000 bytes (1,024 exactly, but rounded off by
the industry to the nearest thousand for ease of calculation). Shown as K
or KB, ten kilobytes is shown as 10K or 10KB.
• Megabyte – Approximately one million bytes and referenced by M or MB.
540 megabytes is shown as 540M or 540MB.
• Gigabyte – Approximately 1 billion bytes (1,073,741,824) and written as
1G or 1 GB.
Microprocessor Basics
Motherboard – Table #1
Microprocessor Basics
• Gigahertz (GHz) Hertz is a measurement of cycles per second (or
frequency). One hertz equals one cycle per second. One megahertz
(1MHz) is equal to one million cycles per second, one gigahertz (1GHz)
is one billion cycles per second. For comparison, the 8088
microprocessor ran at 4.77 MHz, today’s CPUs run at over 2 GHz!
• Register size – The number of bits processed at one time by the
processor. Counted in multiples of 8 bits, such as 8-, 16-, and 32-bit
register size. Sometimes referred to as word size by the computer
industry. Intel’s 8086 processor’s word size was 16 bits or 2 bytes. Most
microprocessors today have 64-bit or 128-bit register sizes.
• Bus – Electronic lines to move the 1s and 0s inside the computer.
Microprocessor Basics
• Internal data bus – Moves the 1s and 0s inside the microprocessor. In
the 8086, there are 16 separate electronic lines, each carrying one 1 or
one 0. The word size and internal data bus were the same size, 16-bit.
• External data bus – Used to connect the microprocessor to adapters,
storage devices, and peripherals. Also called the external data path,
these lines connect to ports and expansion slots. The Intel 8088 had an
8-bit external data bus. Today’s CPUs have 64-bit external data paths.
• Today’s microprocessors have 64-bit or 128-bit internal data bus lines
and external data paths.
Microprocessor Basics
Internal and External Data Buses
Motherboard – Figure #1
Microprocessor Basics
Intel Microprocessors
Motherboard – Table #2
Microprocessor Basics
• Pipelines – Separate (multiple) internal buses that operate
simultaneously. This allows tasks and instructions to be broken down into
smaller and more numerous parts, which permits the CPU to act on them
more quickly and efficiently, improving computer performance.
• SEC (Single Edge Contact) cartridge – Used with an Intel Slot 1
connector on Intel’s Pentium II microprocessor to reach speeds of
300MHz.
• SEPP (Single Edge Processor Package) cartridge – Similar to the
Pentium II SEC and used with the Intel Celeron processor.
Microprocessor Basics
Intel Microprocessors
Motherboard – Figure #2
Microprocessor Basics
Motherboard – Figure #3
Microprocessor Basics
Intel CPU Sockets and Slots
Motherboard – Table #3
AMD Processors
• AMD (Advanced Micro Devices, Inc.) – Produces a microprocessor
similar to the Intel processors.
• Super 7 Socket – Redesigned Socket 7 that allows for higher bus
speeds (66 to 95 or 100MHz). Super 7 motherboards allow higher CPU
speeds, support for AGP and Ultra DMA hard drives, and have advanced
power management features.
• Socket A – 462-pin PGA socket for the AMD Athlon and Duron CPUs.
• Slot A – Used by early AMD Athlon processors similar to Intel Pentium III,
but they are not interchangeable.
AMD Processors
AMD’s Socket A
Motherboard – Figure #4
AMD Processors
AMD Athlon
Motherboard – Figure #5
AMD Processors
AMD CPU Sockets and Slots
Motherboard – Table #4
MMX, SSE, and 3DNOW!
• MMX – A microprocessor technology from Intel that adds 57 instructions
to an Intel processor to help with multimedia and communications
software.
• SSE (Streaming SIMD Extensions) – Intel’s processor technology that
speeds up 3-D applications by allowing instructions to be used by
multiple data items. There are 50 instructions allowing floating-point
calculations to occur simultaneously.
• 3DNOW! – 21 instructions and support for SIMD added to an AMD
processor for 3-D applications.
Processor Speeds and Cooling
 Microprocessors and math coprocessors come in many speeds and this
is measured in gigahertz (GHz). Hertz is a measurement of cycles per
second (or frequency). One hertz equals one cycle per second. One
megahertz (1MHz) is equal to one million cycles per second, one
gigahertz (1GHz) is one billion cycles per second.
 The faster the microprocessor runs, the hotter it gets. Many processors
now have heat sinks (metal bars protruding from the CPU to form a basic
radiator) or small fans for cooling. In many cases, today’s processors
have both. Some systems even have multiple fans to prevent damage to
the processor and internal components due to the amount of heat being
generated.
• Liquid cooling system – liquid is circulated through the system,
including through a heat sink that is mounted on the CPU. It allows higher
clock speeds and is quieter than a fan.
Processor Speeds and Cooling
Microprocessor Speeds
Motherboard – Figure #6
Processor Speeds and Cooling
Microprocessor Fan and Heat Sink
Motherboard – Figure #9
Processor Speeds and Cooling
• Other things to know when determining processor speeds:
– Jumper – Small metal connector with a plastic cover used to connect
two metal pins together. Configuring the jumpers on a motherboard
will change the settings on that board.
– Multiplier – A number that is multiplied by the bus speed to determine
the CPU speed.
• Example: 60MHz bus speed x 1.5(multiplier) = 90MHz CPU
Processor Speeds and Cooling
CPU with Heat Sink and Fan
Motherboard – Figure #10
Processor Speeds and Cooling
JP1 Jumper Block with Pins 1 and 2 Jumpered Together
Motherboard – Figure #11
Cache Memory
• Cache memory – A fast type of memory designed to increase the speed
of microprocessor operations.
• L1 (Level one) cache – Cache memory that is located inside the
microprocessor.
• Write-through cache – The microprocessor writes 1s and 0s into the
cache memory at the same time as regular memory.
• Write-back cache – The 1s and 0s are written to regular memory when
the microprocessor is not busy. It is more efficient than write-through
cache.
• L2 cache – Cache memory that is on the motherboard for Pentium and
lower processors. Starting with the Pentium Pro processor, the L2 cache
is inside the processor packaging and known as on-die cache.
Cache Memory
• L3 cache – L1 and L2 cache are included with the processor packaging.
• COAST (Cache On A STick) – Cache chips on the motherboard that
resemble a small SIMM.
• DIB (Dual Independent Bus) – Two buses used for the processor to
communicate with motherboard components.
• FSB (front side bus) – connects a CPU to the motherboard
components.
• Back side bus – connects the CPU to the L2 cache.
Cache Memory
Front Side Bus
Motherboard – Figure #12
Microprocessor Study Guides
Intel Microprocessor Study Table
Motherboard – Table #6
Microprocessor Study Guides
AMD Processors
Motherboard – Table #7
Microprocessor Upgrade Overview
 Always refer to the motherboard’s documentation when upgrading the
processor. It allows you to choose the proper processor and prevent
damage to the processor and motherboard.
• VRM (Voltage Regulator Module) – Provides the appropriate voltage for
microprocessors. It is usually found on Socket 7 or Socket 8 for
Pentiums.
Installing and Overclocking Microprocessors
• Always refer to the motherboard manuals for the installation steps to
upgrade or install the processor. Your book contains general instructions
for upgrading and installing the microprocessor beginning on page 2-25.
• Overclocking – Changing the front-side bus speed or the multiplier to
boost the CPU speed or system speed. This can cause damage to the
CPU, motherboard, or other components.
Installing and Overclocking Microprocessors
Computer Case Auxiliary Fans
Motherboard – Figure #14
Dual Processors
• Adding another (or dual) processor can greatly enhance computer
performance. Most home and business users do not require an additional
processor, however most servers do.
• Follow all manufacturers documentation on selecting an additional
processor, installing it, and configuring the motherboard with dual
processors.
• Its important to add RAM if possible when adding a second processor.
Put in as much RAM as the customer can afford to improve performance.
A general rule of thumb is to double the RAM when adding a second
processor.
Motherboard Troubleshooting
 Motherboard and power problems are probably the most difficult things to
troubleshoot. A good general list of motherboard troubleshooting tips can
be found on page 2-29 in your book.
Expansion Slots
• Expansion slots allow adapters to be installed into the motherboard to
add capabilities to the PC.
• Technicians must be able to identify expansion slots and distinguish
between the adapters that use them.
• The technician must be able to install the proper adapter in the correct
expansion slot and configure both correctly.
ISA (Industry Standard Architecture)
• ISA (Industry Standard Architecture) – The oldest expansion slot that
is configured in 8-Bit and 16-Bit slots.
– Also referred to as the AT bus.
– Operates at 8MHz, although some manufacturers reliably achieve a
throughput of 10 MHz.
Motherboard – Figure #15
EISA (Extended Industry Standard Architecture)
• EISA (Enhanced Industry Standard Architecture) – 32-bit expansion
slot that is the same length as an ISA slot and twice as deep.
– A non-proprietary architecture developed by a group of nine vendors
in response to IBM’s proprietary MicroChannel Architecture.
– A 32-bit, 10MHz standard that also allows ISA adapters to operate in
the expansion slots.
– This standard was never as successful as the designers hoped.
PCI (Peripheral Component Interconnect)
• PCI (Peripheral Component Interconnect) – The most popular
expansion slot that is configured in both 32-bit, 33MHz and 64-bit, at
33MHz and 66MHz.
• A new standard is the PCI-X which can operate at 66MHz, 133MHz,
266MHz, and 533MHz. PCI-X 1066MHz is being developed.
• PCI adapters are configured with software and the standard supports
bus-mastering, which allows an adapter to take over the external bus
from the CPU and execute operations with another bus-mastering
adapter without going through the processor.
PCI (Peripheral Component Interconnect)
PCI-X Block Diagram
Motherboard – Figure #17
PCI (Peripheral Component Interconnect)
3.3 Volt and 5 Volt PCI Expansion Slots
Motherboard – Figure #18
PCI (Peripheral Component Interconnect)
Motherboard – Figure #19
Mini PCI
• Mini PCI – 32-bit, 33MHz standard was developed to allow PCI upgrades
and interface cards to be added to laptops, docking stations, and printers.
Mini-PCI cards have 3 form factors; Type I, Type II, and Type III.
Mini PCI Adapter
Installed in Laptop
Motherboard – Figure #20
AGP (Accelerated Graphics Port)
• AGP (Accelerated Graphics Port) – 32-bit bus interface for graphics
adapters developed from the PCI bus.
– It speeds up 3-D graphics, 3-D acceleration, and full-motion playback.
– Allows the video adapter to directly access RAM on the motherboard
when needed.
– The video subsystem is isolated from the rest of the computer.
– In order to implement AGP, the motherboard must have an AGP
expansion slot, the chipset must support AGP, and an operating
system that supports AGP must be installed.
– Some motherboards will allow changing the amount of memory AGP
can use. The amount normally used is 64MB, configured through
BIOS settings, and referred to as the AGP Aperture.
AGP (Accelerated Graphics Port)
AGP Versions
Motherboard – Table #8
AGP (Accelerated Graphics Port)
AGP Expansion Slot
Motherboard – Figure #22
More Motherboard Connectors
• AMR (Audio/Modem Riser) – Connector on the motherboard for
combination audio and modem adapters without taking up a PCI slot.
• CNR (Communications Network Riser) – Intel’s design that allows the
integration of network, audio, and modem functions. It shares a PCI slot
and is located beside or between other motherboard expansion slots.
• ACR (Advanced Communication Riser) – Technology that supports
audio, modem, networking, and DSL modems. It was developed by a
group of companies including AMD, VIA Technologies, Motorola, and
3Com.
Future Buses
• HyperTransport – AMD’s futuristic I/O architecture in which a serial-link
design allows devices to communicate in a daisy chain fashion.
• InfiniBand – A futuristic I/O architecture wherein point-to-point device
connections are made through a switching fabric.
• HCA (Host Channel Adapter) – Connects memory to a switch fabric and
is used in the InfiniBand bus architecture.
• TCA (Target Channel Adapter) – An adapter that connects end devices
to the switch fabric and is used in the InfiniBand architecture.
• RapidIO – A futuristic I/O architecture that supports interconnections for
chip-to-chip, board-to-board, and device-to-device.
Proprietary Expansion Slots
 Some older computers have an expansion slot built into the motherboard
that are neither ISA nor PCI. These are proprietary expansion slots that
only fit proprietary adapter cards. These are only available from the
expansion slot manufacturer (if still supported) and usually expensive.
USB (Universal Serial Bus)
• USB (Universal Serial Bus) – Allows connection of up to 127 external
devices without degradation of speed. Can be used by many types of
devices as long as the operating system supports USB.
– Original USB includes two speeds:
• 1.5Mbps for keyboards and mice.
• 12Mbps for modems, CD/DVD drives, printers, scanners, monitors,
and digital cameras.
– USB version 2.0 supports speeds up to 480Mbps for
videoconferencing cameras, higher resolution printers and scanners.
It is backward compatible for USB 1.1 devices.
– USB has two types of USB ports and connectors – Type A and Type
B.
USB (Universal Serial Bus)
USB Type A and Type B Connectors
Motherboard – Figure #27
IEEE 1394 (FireWire or I.Link)
• IEEE 1394 – known as FireWire and supports up to 63 devices. It is able
to support digital audio and video devices.
– Supports plug and play like USB and the devices are hot swappable.
– The IEEE 1394 bus is actually a peer-to peer standard meaning a
computer is not needed to use it, such as connecting a digital camera
directly to a hard drive to transfer picture files.
– Designed to support high-speed audio and video devices with greater
throughput for applications such as video conferencing.
– All versions of IEEE 1394 support speeds of 100, 200, 400, 800 or
1200 Mbps and a maximum distance of 236 feet or 328 feet for
IEEE1394b.
IEEE 1394 (FireWire or I.Link)
• IEEE 1394 – known as FireWire and supports up to 63 devices. It is able
to support digital audio and video devices.
Motherboard – Figure #28
PC Card
• PC Card – Previously known as PCMCIA (Personal Computer Memory
Card International Association). It is used for modems, hard drives,
network adapters, etc. in laptop computers.
• CardBus – Allows 32-bit transfers at speeds up to 33MHz.
• SmartMedia – Holds pictures and audio files and is used with digital
cameras, PDAs, etc.
• ZV port (Zoomed Video Port) – Allows direct data transfer from a PC
Card to a video controller. Data transfers over the ZV bus instead of the
system bus.
• CardBay – Allows laptop computers to be compatible with the USB and
IEEE 1394 serial interfaces.
PC Card
PC Card
Motherboard – Figure #30
PC Card
PC Cards
Motherboard – Table #9
PC Card
Expansion Slot or Port Overview
Motherboard – Table #10
Chipsets
• Chipset – The principle chips on the motherboard that work in
conjunction with the microprocessor and allow features on a computer.
• For example, they control:
– Maximum amount of motherboard memory
– The type of RAM chips
– The motherboard’s capacity for multiple processors
– Support for the latest version of PCI
Types of Motherboards
• Form Factors – The different sizes of motherboards.
• The most common motherboards are:
– AT: named after IBM’s original AT computer motherboard.
– Baby AT: smaller size of the AT.
– ATX: similar to baby AT, but rotated 90 degrees.
– NLX: designed around Pentium II and higher, allows more expansion.
– MicroATX: max size is 9.6 inches by 9.6 inches, fits ATX case.
– FlexATX: 9 inches by 7.5 inches and backward compatible with ATX and
MicroATX.
– ITX: 8.5 inches by 7.5 inches and made for a smaller power supply.
– WTX: for large workstations and servers.
Types of Motherboards
NLX Motherboard
Motherboard – Figure #24
Upgrading and Replacing Motherboards
• There are several issues to be taken into account when upgrading a
motherboard:
– Memory
– Adapter types
– Type of case
– Microprocessor
– Chipsets
– Hard drive
– Power supply
– Future upgrade-ability
– There is a basic guide on page 2-51