(^34) PC Hardware: A Beginner’s Guide
External Power Issues
The PC’s power supply solves the internal power issues for the computer, but many of
the PC’s power problems are caused by the original power source. Although we tend to
take electrical power for granted most of the time, that is, until it is not there, electrical
power can be a very unstable, damaging force that the PC needs to be protected against.
Chapter 23 covers the many ways that the PC can be protected, but this is a serious
enough problem that it bears mention here as well.
Electrical power tends to fluctuate in its voltage. While its normal operating range can
vary, it is usually between 95 and 125 volts. On occasion though, the current spikes above or
drops below its normal range and causes damage to a PC that is unprotected from sudden
changes in the current. The best way to protect your PC is with a surge suppressor or an
uninterruptible power supply (UPS). Chapter 23 will explain these devices in more detail.Protecting Against ESD
One of the most insidious destroyers of PC circuits iselectrostatic discharge(ESD), which
can occur when you touch the fragile electronic components of the PC.Static electricityis
what makes your hair stand straight u pwhen you rub a balloon on it, or it gives you a
shock after you walk across the carpet and grab the doorknob. Certain fabrics, fibers, and
materials naturally generate static electricity, and the human body has a tendency to
absorb and hold it until it finds a way to discharge it as an electrical flow. Except for
the tingle in your hand, this is usually a fairly innocent and undamaging phenomenon.
However, when it is the electronic components on your PC’s motherboard or any of its
other circuits, such as adapter cards, that receives the spark, it is more than likely that
some damage has taken place.
Just because you can’t feel, see, or hear ESD, doesn’t mean it won’t damage your com-
puter. You can feel an electrostatic discharge of around 3,000 volts, but it only takes 30
volts to fry some of the electronics on an electronic circuit card, including the mother-
board. Most of the electronics inside the computer are made to use from 1 to 12 volts of
DC power, so it is no wonder that a charge with higher voltage may do damage. (Just for
the record, any ESD that you can see has around 20,000 volts, which is why it hurts.)
To protect your computer, always follow the ESD safety guidelines for your PC. The
safest thing to do is to always wear an antistatic wrist stra p(see Figure 2-6) anytime you
open your computer case. Other precautions are available, but wearing a wrist strap is
probably the easiest and safest way to protect your computer. Chapter 23 covers some of
the other ways you can protect your PC.