Datasheet
Identifying Motherboards
23
ATX Most system boards today use the ATX (Advanced Technology Extended) form
factor. It provides many design improvements over the AT, including I/O ports built
directly into the side of the motherboard, the CPU positioned so that the power-supply
fan helps cool it, and the ability for the PC to be turned on and off via software. It uses
a PS/2-style connector for the keyboard. The expansion slots are parallel to the narrow
edge of the board. See Figure 1.11.
FIGURE 1.11 An ATX-style motherboard
CPU
Expansion slots
parallel to narrow
edge
Power supply
connector
Built-in ports
BTX The Balanced Technology Extended (BTX) motherboard was designed by Intel
to deal with issues surrounding ATX (heat, power consumption, and so on). The BTX
mother board is larger than ATX, so there is more room for integrated components; there
is also an optimized airflow path and a low-profile option.
Micro ATX The micro ATX (most commonly written as microATX) was released in
1997 for smaller—and typically cheaper—systems. It has become popular in recent years
in low-cost PCs. The maximum size of a micro ATX motherboard is 244mm square, com-
pared to 305mm
×244mm for a standard ATX motherboard. The micro ATX is backward
compatible with the ATX.
NLX An acronym for New, Low profile eXtended, this form factor is used in low-profile
case types. It incorporates expansion slots that are placed on a riser board to accommodate
the reduction in case size. However, this design adds another component to troubleshoot.
I/O Interfaces
While there are many types of I/O (input/output) interfaces available, the key ones to know
for this portion of the exam are USB and IEEE 1394/FireWire, as the others are discussed
in other places in this chapter and inclusion here would be repetitive.
USB USB is a newer expansion bus type that is used almost exclusively for external
devices. All motherboards today have at least two USB ports. Some of the advantages of
USB include hot-plugging and the capability for up to 127 USB devices to share a single set
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