Datasheet

6 Chapter 1
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Personal Computer System Components
With integrated system boards, there is a way around having to replace the whole mother-
board when a single component breaks. On some motherboards, you can disable the malfunc-
tioning onboard component (for example, the sound circuitry) and simply add an expansion
card to replace its functions.
System Board Form Factors
System boards are also classified by their form factor (design): ATX, micro ATX, BTX,
or NLX (and variants of these). Exercise care and vigilance when acquiring a motherboard
and case separately. Some cases are less flexible than others and might not accommodate
the motherboard you choose.
Advanced Technology Extended (ATX)
The ATX motherboard has the processor and memory slots at right angles to the expansion
cards. This arrangement puts the processor and memory in line with the fan output of the
power supply, allowing the processor to run cooler. And because those components are not in
line with the expansion cards, you can install full-length expansion cards in an ATX mother-
board machine. ATX (and its derivatives) are the primary motherboards in use today.
Micro ATX
One form factor that is designed to work in standard ATX cases, as well as its own
smaller cases, is known as micro ATX (also referred to as μATX). Micro ATX follows the
same principle of component placement for enhanced cooling over pre-ATX designs but
with a smaller footprint. With this smaller form come trade-offs. For the compact use of
space, you must give up quantity: quantity of memory modules, quantity of motherboard
headers, quantity of expansion slots, quantity of integrated components, even quantity of
micro ATX chassis bays, although the same small-scale motherboard can fit into much
larger cases, if your original peripherals are still a requirement.
Be aware, however, that micro ATX systems tend to be designed with power supplies of
lower wattage, in order to help keep down power consumption and heat production, which
is generally acceptable with the standard micro ATX suite of components. As more off-
board USB ports are added and larger cases are used with additional in-case peripherals,
larger power supplies might be required.
New Low-Profile Extended (NLX)
An alternative motherboard form factor, known as New Low-Profile Extended (NLX), is
used in some low-profile case types. NLX continues the trend of the technology it succeeded,
Low Profile Extended (LPX), placing the expansion slots (ISA, PCI, and so on) sideways on
a special riser card to use the reduced vertical space optimally. Adapter cards, or daughter-
boards, that normally plug into expansion slots vertically in ATX motherboards, for exam-
ple, plug in parallel to the motherboard, so their most demanding dimension does not affect
case height. Figure 1.2 shows a low-profile motherboard with its riser card attached.
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