Hardware Reference
In-Depth Information
more PCI Express expansion cards becoming available over the com-
ing months and years and PCI expansion cards becoming increasingly
hard to find.
Communications ports
All motherboards provide various communications ports. Most still pro-
vide at least one legacy serial port and parallel port, although these ports
are now often present only as header-pin sets on the motherboard rather
than as physical connectors on the rear I/O panel. If you need to use them,
you'll need to install a cliffhanger bracket (usually supplied with the retail-
boxed motherboard) to extend the ports out to an expansion slot cover.
Beyond these legacy ports, current motherboards may provide some or
all of the following communication ports:
USB 2.0
All current motherboards provide multiple USB 2.0 ports, both as phys-
ical connectors on the rear I/O panel and as header-pin sets that can
be extended to the front-panel connectors. Most current peripherals—
from keyboards and mice to speakers, printers, scanners, and digital
cameras—use the USB 2.0 interface, so it's important to have enough
for your needs. (Of course, you can always add a USB hub, but that
increases costs and desktop clutter.) Look for a motherboard with at
least six USB 2.0 ports; eight or more is better.
USB 3.0
The most recent USB standard, USB 3.0, will eventually replace USB
2.0, just as USB 2.0 eventually replaced USB 1.0 and USB 1.1. The
raison
d'être
for USB 3.0 is speed. USB 2.0 has a nominal data rate of 480 Mb/s
(60 MB/s) and typical real-world throughput (after protocol overhead)
of 25 MB/s. For most peripherals, that's more than fast enough, but it's
marginal for such high-speed peripherals as external hard drives.
USB 3.0 has a nominal raw data rate of 4 Gb/s (500 MB/s) and real-world
throughput of about 400 MB/s, fast enough even for external hard
drives and solid-state drives. USB 3.0 is also backward-compatible with
devices that use earlier USB standards, although those devices still
run at the lower data rates for which they were designed.
Eventually, USB 3.0 ports will be ubiquitous, but for now most
motherboards do not provide any USB 3.0 ports at all. Those that do
generally provide only one or two, in combination with several USB
2.0 ports. As devices that need the higher speed of USB 3.0 and chip-
sets that support USB 3.0 become more common, more motherboards
will start including USB 3.0 ports. For now, we consider USB 3.0 sup-
port a nonissue. If you later need USB 3.0, it will be easy enough to
buy an inexpensive USB 3.0 PCI Express adapter card and install it in
your system.
eSATA
Many current motherboards provide eSATA ports, sometimes as in-
ternal connectors, sometimes on the rear I/O panel, and sometimes
both. These ports are used primarily to connect external hard drives
