(^358) PC Hardware: A Beginner’s Guide
AT The IBM PC AT, while not much different on the outside, was quite
different on the inside. The AT had a larger power supply, and the motherboard
and power supply were repositioned inside the case. Because of IBM’s policy
of open systems, the AT quickly became the form factor of choice among
manufacturers. The AT established the form factor on which all subsequent
form factors, deskto pand tower, have been based, one way or another.
LPX Although never officially accepted as a standard form factor, LPX is the
oldest of the “low profile” form factors. It has been around since the late 1980s
and over the past ten years or so has been one of the most popular slimline
form factors sold. Slimline cases are a little shorter than the cases used with
a Baby AT or ATX form factors. This is achieved by moving expansion cards
to a riser board that mounts them horizontally in the case instead of vertically,
thereby saving inches of height.
MicroATX and FlexATX These two ATX-based form factors define
specifications for motherboards smaller than the MiniATX and the NLX.
Technically, MicroATX and FlexATX do not define a case form factor, but
manufacturers are designing proprietary cases to take advantage of the smaller
size (9 inches by 7.5 inches) of these motherboards. These form factors are
intended for PCs targeted to the mass market and home users. Figure 15-15
shows In-Win’s FlexATX PC case, which is designed for mass-market appeal.
WTX This form factor goes in the opposite direction of the MicroATX and FlexATX
standards. ItsWstands for workstation, and it is a form factor intended for high-
performance workstations and servers. This form factor defines a modular case
that features a larger motherboard footprint that is twice the size of an ATX
motherboard. A WTX case features space for high-capacity, redundant power
supplies, removable panels for easy access to components, a large number of
hard drive bays, and support for multiple cooling fans. See Figure 15-6 (shown
previously) for an example of a WTX form factor computer.
For more information on PC form factors as they relate to motherboards and power
supplies, see Chapters 3 and 14, respectively.
System Case Features
Depending on its form factor and from whom you purchased it, your system case will
probably include some preinstalled components and features (see Figure 15-16). These
componentsandfeatures,whichareexplainedinthefollowingsections,areusuallytheop-
tional pieces that conform a generic case to fit a particular form factor and your particular
requirements. As several of the form factors are very close in their size and component
placement, manufacturers make cases that can be used with a number of form factors. Ap-
plying such items as an I/O template, the appropriate power supply, and motherboard
mounts turns a generic case into a custom case that’s just right for your needs.