Current socket arrangements are often named for the
number of pins in the PGA. Commonly used sockets are:
• Socket 478 - for older Pentium and Celeron processors
• Socket 754 - for AMD Sempron and some AMD Athlon
• Socket 939 - for newer and faster AMD Athlon
• Socket AM2 - for the newest AMD Athlon processors
• Socket A - for older AMD Athlon processors
Anyone who already has a specific CPU in mind should
select a motherboard based on that CPU.
The newest Intel CPU does not have a PGA. It has an
LGA, also known as Socket T. LGA stands for Land Grid
Array. An LGA is different from a PGA in that the pins
are actually part of the socket, not the CPU.
Computer hardware, such as memory, PCI and
AGP connect to the motherboard through slots.
The chipset is the "glue" that connects the microprocessor
to the rest of the motherboard and therefore to the rest
of the computer. On a PC, it consists of two basic parts
-- the north bridge and the south bridge.
A bus is simply a circuit that connects one part of the
motherboard to another. The more data a bus can handle
at one time, the faster it allows information to travel.
Computer memory has a big effect on system
performance. Pictured above is SIMM memory,
or single in-line memory module, which is a type
of RAM memory module.
DIMM, or dual in-line memory module, has a 64-bit path to
memory chips, whereas the SIMM has only a 32-bit
(184-pin DDR DIMM RAM
in the photo)
SODIMM, or small outline dual in-line memory module, is
made with integrated circuits and is about half the size of
DIMM modules. (200-pin DDR SODIMM RAM in the
A RAM upgrade can greatly extend your
The basic input-output system BIOS is the first
thing you see when you turn on your computer.
A microprocessor -- also known as a CPU or central
processing unit -- is a complete computation engine that
is fabricated on a single chip.
64-bit processors have entered the mainstream,
such as this eight-generation Athlon processor.
A hard disk is a sealed aluminum box, which has been
opened in this photo. The controller electronics are
attached to one side, controlling the read/write
mechanism and the motor that spins the platters.
This hard drive has three platters, also called hard
disks, and six read/write heads.
The arm on a hard disk holds the read/write heads
and has to be incredibly fast and precise. There
is one arm per read/write head, and all of them
are lined up to form one unit.
Storing the Data
Data is stored on the surface of a platter in sectors and
tracks. Tracks are concentric circles, and sectors are
pie-shaped wedges on a track.
The Integrated Drive Electronics interface was the
most popular way to connect a hard drive to a PC.
SATA (Serial ATA) Interface
• Serial ATA (SATA) hard drives have become the new
standard in hard drive technology.
• SATA hard drives result in less clutter and increased
airflow in the computer system, because SATA cables
are dramatically narrower than EIDE cables.
The Peripheral Component Interconnect (PCI) bus
provides direct access to system memory for
connected devices. PCI slots can be used for
network, graphics and sound cards.
PCI cards use 47 pins to attach to a PCI slot. Pins
are thin metal feet that allow computer chips to
be attached to a circuit board.
PCI Sound Card
A sound card allows a computer to create and
record real, high-quality sound.
An AGP, or accelerated graphics port, allows the
operating system to designate RAM for use by
the graphics card (like the one above) on the fly.
Like a motherboard, a graphics card is a printed
circuit board that houses a processor and RAM.
PCI Express or PCIe eliminates the need for the
AGP by accepting more data and supplying
more power to video cards.
Just about any computer that you buy today
comes with Universal Serial Bus connectors let
you attach everything from mice to printers.
PC power supplies use switcher technology to convert the
AC input to lower DC voltages. The 3.3- and 5-volts are
typically used by digital circuits, while the 12-volt is used
to run motors in disk drives and fans.
This PC power supply has been removed from its
PC case. The small, red switch at right, above
the power-cord connector, is for changing line
voltages in various countries.
In this photo you can see three small transformers
(yellow) in the center. To the left are two
cylindrical capacitors. The large finned pieces of
aluminum are heat sinks.
Laptops are different from desktops only in how
the components are put together.
Because of this fundamental design difference and because of a laptop's
inherent portability, components have to:
• Fit into a compact space
• Conserve power
• Produce less heat than desktop components
• Runs at a lower voltage and clock speed
• Mounts to the motherboard without using pins
• Has a sleep or slow-down mode
Laptop Heat Sink and Fan
Laptops usually have small fans, heat sinks, heat
spreaders or heat pipes to help dissipate the
heat from the CPU.
Laptop Heat Sink and Fan
Here you can see a heat sink and fan in a laptop,
similar to the hardware in a desktop.
Lapto-ps often use smaller memory modules to save
space. Memory types used in laptops include:
• Small Outline Dual Inline Memory Module (SODIMM)
• Dual Data Rate Synchronous RAM (DDR SDRAM)
• Single data rate Synchronous RAM (SDRAM)
• Proprietary memory modules
A graphics processing unit (GPU)
Most laptops have graphics capability built into the
motherboard or have smaller graphics cards
with a GPU designed specifically for laptop use.
Laptop LCD Screen
A laptop displays its graphics on a liquid crystal
display (LCD) screen. Most screens measure
between 12 and 17 inches, and the size of the
screen affects the overall size of the laptop.
LiIon batteries are the current standard for laptop
computers. They are light and have long life spans. They
do not suffer from the memory effect, can be charged
randomly, and won't overheat if overcharged. They are
also thinner than any other battery available for laptops,
making them ideal for the new ultra-thin notebooks. LiIon
batteries can last for anything from about 950 up to 1200