Building Your Own PC! - The Motherboard is the Core of the PC
The single most important piece of hardware that you will buy is the motherboard - the
very core of your PC. The processor plugs into it, drives connect to it with cables,
expansion cards live in special slots and everything else, from the mouse to the printer,
is ultimately connected to and controlled by the motherboard. If you buy a PC from a shop,
chances are you'll never think about or even see the motherboard; but when you build a
system from scratch, it must be your primary consideration. Everything else follows from here.
Form factor: This is the way of describing the motherboard's size and shape,
important because it involves industry-wide standards and ties in with the computer case
and power supply. Form factors have evolved through the years, culminating since 1995 in
a popular and flexible standard known as ATX. Not just one ATX standard, of course: there
are MiniATX, MicroATX and FlexATX motherboards out there, all progressively slimmed-down
versions of full-size ATX.
The upside of a smaller motherboard is that you can use a smaller case and reduce the
overall dimensions of your computer; the downside is a corresponding reduction in expandability.
A full-sized ATX motherboard can have up to seven expansion slots while a MicroATX
motherboard is limited to four.
One technical benefit of ATX over the earlier BabyAT form factor from which it directly
evolved is that full-length expansion cards can now be fitted in all slots; previously,
the location of the processor and memory on the motherboard meant that some slots could
only take stumpy (not a technical term) cards. Another is the use of a double-height
input/output panel that lets motherboard manufacturers build-in more integrated features.
All in all, it's a definite improvement.
But from your point of view, the main attraction has to be the guarantee that any ATX
motherboard, including the smaller versions, will fit inside any ATX computer case. That's
the beauty of standards.
Chipset: The real meat of a motherboard resides in its chipset: a collection of
microchips that together control all the major functions. Without a chipset, a motherboard
would be lifeless; with a duff chipset, it may be inadequate for your needs. Indeed, as
one motherboard manufacturer explained it to us, the chipset is the motherboard: don't ask
what this or that motherboard can do -ask instead what chipset it uses and there you'll
find your answer.
So what does a chipset do, precisely? Well, at one level it controls the flow of data
between motherboard components through a series of interfaces. Each interface, or channel,
is called a bus. The most important buses are:
FSB (Front Side Bus). The interface between the Northbridge component of the chipset and the processor.
Memory bus. The interface between the chipset and RAM.
AGP (Accelerated Graphics Port). The interface between the chipset and the AGP port.
This is gradually disappearing from motherboards as more and more video cards are designed
for the PCI Express slot.