UPGRADING REPAIRING PCs

LPX Motherboard
Motherboard Form Factors 31
Since 1987, many low-cost systems have used variations on this layout,
which features a single slot used for a riser card. The expansion
cards for video, audio, and so forth are connected to the riser card,
not the motherboard. Most LPX systems use riser cards that mount
the expansion slots parallel to the motherboard; some use a T-shaped
riser card that keeps the expansion slots at their normal upright position.
Additionally, most LPX systems have built-in video, audio, and
other I/O ports. Unfortunately, because its details were never standardized,
it is virtually impossible to upgrade. Systems with this
motherboard are essentially disposable (see Figure 2.2).
Figure 2.2 Typical LPX system chassis and motherboard.
ATX Motherboard
Since mid-1996, the ATX motherboard has become the standard
for most systems using non-proprietary motherboards (see Figure
2.3). Similar to Baby-AT, it’s also an industry standard, and similar
to LPX, it features built-in ports. Compared to both, though, it
offers much greater ease of upgrading and servicing. ATX motherboards
are rotated 90 degrees when compared to Baby-ATs and also
use a different power supply for advanced power management features.
Because of their built-in ports and differences in layout, ATX
motherboards require an ATX case. ATX cases can also be used for
Baby-AT motherboards, though. Figure 2.3 shows a full-size ATX
layout; however, several smaller versions now exist, including
mini-ATX, micro-ATX, and flex-ATX.