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 motherboard machine.

ATX (and its derivatives) are the primary motherboards sold 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 example, plug in parallel to the motherboard, so their most demanding dimension does not affect case height.

LPX, a technology that lacked formal standardization and whose riser card interfaces varied from vendor to vendor, enjoyed great success in the 1990s until the advent of the
Pentium II processor and the Accelerated Graphics Port (AGP).

These two technologies placed a spotlight on how inadequate LPX was at cooling and accommodating high pin counts.

NLX, an official standard from Intel, IBM, and DEC, was designed to fix the variability and other
shortcomings of LPX, but NLX never quite caught on the way LPX did.

Newer technologies, such as micro ATX, and proprietary solutions have been more successful and have taken even more market share from NLX.

Balanced Technology Extended (BTX)

In 2003, Intel announced its design for a new motherboard, slated to hit the market mid- to
late-2004. When that time came, the new BTX motherboard was met with mixed emotions.

(Postpone accusations of acronym reverse-engineering until “CTX” is announced as the name
of the next generation.)

Intel and its consumers realized that the price for faster components
that produced more heat would be a retooling of the now-classic (since mid-1990s) ATX
design.

The motherboard manufacturers saw research and development expense and potential
profit loss simply to accommodate the next generation of hotter-running processors, processors
manufactured by the same designers of the BTX technology.

It was this resistance that caused the BTX form factor to gain very little ground over the next couple of years. Nevertheless, with the early support of Gateway, Inc., and later buy-in of Dell, Inc., the BTX design dug in and charted a path for future success.

Marketing aside, the BTX technology is well thought out and serves the purpose for which
it was intended.

By lining up all heat-producing components between air intake vents and the power supply’s exhaust fan, Intel found that the CPU and other components could be cooled
properly by passive heat sinks.

Fewer fans and a more efficient airflow path create a quieter configuration
overall.

While the BTX design benefits any modern onboard implementation, Intel’s
recommitment to lower-power CPUs has at once lessened the need to rush to more expensive
BTX systems and given the market a bit more time to assimilate this newer technology.

There are other motherboard designs, but these are the most popular and also the ones that are covered on the exam.

Some manufacturers (such as Compaq and IBM) design and manufacture their own motherboards, which don’t conform to the standards. This style of motherboard is known as a proprietary design motherboard.