The Shocking Truth: Electricity and Your PC

The electrical utility poles (or underground utility cables) along your road or street can carry whopping amounts of power, starting at around 7,200 volts and moving upwards; 7,200 volts represents something called a phase, and utility poles may carry multiple phases. The power coming into your home or small office is most likely a 240-volt current. It usually arrives in two wires carrying 120 volts each, plus a bare ground wire. By itself, 120-volt current can power many of the normal appliances and devices in your home, including your PC. Heavy-duty appliances such as a refrigerator, an air conditioner, a large copying machine, or major power tools may need the full 240 volts.

Along with the number of volts, regulating that voltage is an issue because it doesn’t always flow at a nice, even rate. If you graphed the power state for one of your 120-volt lines, you’d see that it fluctuates wildly, creating an often-dramatic sine wave pattern of peaks and valleys. And this is operating under normal conditions, not taking into account events such as brownouts, blackouts, and power surges that can make that pattern even more dramatic and variable.

This isn’t a random accident: this is what is known as alternating current (AC). But beyond the variation naturally built into alternating current are added variables based on factors such as distance from a power sub-station, the quality of the lines carrying the power to you, and even the wiring in the building you’re living or working in. The use of other appliances, large and small, also affect that electrical stability. By the time all these other factors come into play with the energy being delivered to your modest little outlet, your power can be pretty dirty.

What is “dirty power”? Those peaks and valleys I said you would see if you graphed your electrical flow aren’t all nice and neat and uniform. As a refrigerator or freezer case kicks in, as you turn a big appliance off, or as a malfunctioning electrical appliance such as a toaster misbehaves, you can see those peaks turn into a series of shuddering spikes. Bad or older wiring can produce some erratic behavior in power flow, too. Such conditions are often referred to as dirty power, because fluctuations exceed normal operating ranges.

How bad can it really be, you may wonder. After all, other appliances plugged into regular wiring in your home or office seem to keep working through these fluctuations.

It’s a good question without a simple answer. For instance, some devices are engineered to be more tolerant of these power highs and lows. Really, any electrical device that didn’t take into account some of these fluctuations probably wouldn’t last long.

This brings me to an important and often-overlooked point: You don’t have any accurate way of judging—barring a rare situation where a power surge kills a piece of equipment or an appliance—how much your dirty power contributes to early appliance failures in your living and work spaces. I can’t say with any certainty that the television I had to replace after eight years might have lasted 12–15 years had it been protected from these fluxes. What you do know is that, among unprotected equipment especially, such fluxes can damage appliances and equipment; it’s the degree and the volume that I must leave to the engineers to debate.

However, I wouldn’t be doing this topic justice if I didn’t talk about the role that circuit breakers (for most of us) and fuses (in older buildings) play in protecting you from the problems that can arise from electricity and the devices that require it.

Power lines from external poles or underground cabling typically come into the house through the circuit breaker box or the fuse box. Each of these boxes acts as a buffer between your building’s wiring and the rest of the power system. For example, when you have some types of power surge, your circuit breakers or fuses should take the brunt of the force. The circuit breakers will trip, requiring you to reset them, while the fuses will likely blow, demanding that you replace them before you can restore power.

Likewise, circuit breakers or fuses protect you from the worst effects of an electrical problem that may occur within your home or office. Without circuit breakers or fuses, a broken wire can much more readily start a fire or potentially electrocute you.

Yet these intermediaries won’t protect you from everything. If they did, you’d never see your lights flicker. A lot of damage can still be inflicted on delicate electronics by serious power variations, which is why surge-protection devices for consumer electronics and appliances appear to be gaining in popularity. After all, no one wants to buy a new 40" TV and lose it the next day, as one of my friends did, to an electrical storm.

Tip 

Having worked in locations where fuse boxes were used and locations where circuit breakers were located, I strongly recommend upgrading a fuse box-based building with circuit breakers. Circuit breakers make it substantially faster and easier to cut power in an emergency, they can be reset (rather than replaced as fuses need to be), and you won’t burn your hand trying to remove a hot fuse (which can create an electrical fire).

Let’s look at the issue of power—both dirty and otherwise, although many argue that all the power you use is pretty dirty—and its relationship to your PC. The first stop in this discussion is the PC power supply, the vital intermediary between your wall outlet and your motherboard and other components.

Note 

For those of you with a better understanding of electricity than most, please understand that I kept this topic purposely simple.

A Cautionary Tale: Building a Healthy Respect Based on Intense Pain

When I was a young teenager, my parents’ old home was poorly wired and we had a number of incidents related to lightning. After years of going out and standing in the middle of a field to watch violent electrical storms because the power of them fascinated me more than scared me, I happened to be turning off a brass floor lamp one afternoon when lightning entered the house. Sometime after I discovered I had traveled about five feet across the room from the zap I received as the lightning centered itself on the metal lamp I was touching, I developed a healthy respect for lightning.

Later, when I first started working with PC hardware, I had a similar learning curve with the electrical side of computers. I was pretty sure those instructions telling you to “power off and remember to ground yourself” were for nervous people who weren’t careful as they worked.

My foolhardiness was bolstered by the fact that I had managed to get away with swapping several pieces of hardware in which I’d bent the rules about grounding and power disconnection; the hardware was fine afterwards and so was I. Sure, powering down, disconnecting, and grounding doesn’t take much time. But in the days before hot-swapping hardware, you had to power down, install, and then power up again to have every newly installed device recognized (as you still do for many devices today).

Then one day, after this string of irrational successes, I was working on my PC with the cover off because I was testing. I happened to notice a string of dust hanging from the power wires just above the memory sockets. Without thinking, I stuck my hand inside the live, powered PC to grab the string. But the string got wrapped around something, so I ended up pulling harder than I might have expected. When it finally came loose, my hand slipped, hit the edges of my installed memory, and I heard a popping noise in the PC somewhere around the time my ears began to ring thunderously.

Gee, I guess there’s a reason you’re not supposed to do that!

The good news is that my ear-ringing stopped after a few days, and that only my PC memory was damaged. The bad news is that PC memory at the time was far more expensive than it is now; a problem with chip supply that year had lifted the price to more than $40 per megabyte, and I had to replace 16MB.

Some lessons are just more expensive than others.

Role of the Power Supply

The PC’s power supply sits between your home or office current and the PC electronics itself. It expects a reasonably steady flow of 120 volts operating at roughly 60 cycles to empower it so it can provide power to the rest of the PC.

But the power supply isn’t just a simple intermediary. Instead, part of a power supply’s job is to convert the AC flowing to it into direct current (DC) required by your PC components before it pushes that power out into the system through the connectors plugged into components such as the motherboard and the drives.

Like other devices, the power supply has a degree of fault tolerance built into it that allows for some fluctuation in power before it begins to affect the flow of power to the PC. But most power supplies aren’t designed to withstand massive fluctuations. When hit by them, a power supply may simply shut down (either temporarily until you restart the system or permanently because it sustained damage). Or it may continue to work, but the clock may have started ticking on the day that power supply will fail. Subsequent power problems may hasten this date along.

I’ll tell you more about differences in power supply quality in a moment.

Warning 

Why is it so important for you to unplug your PC when you work? Whether you realize it or not, even when your PC is turned off, a small amount of current continues to pass from the PC power supply to the motherboard. The amount may sound minute compared to the zap potential when the PC is turned on, but it’s enough to cause damage to the components. You might not enjoy it too much either.

Some Symptoms of a Failing Power Supply

While many times a PC power supply seems to fail quickly and without prior notice, you can often pick up subtle and not-so-subtle symptoms before the actual failure occurs. Some of these symptoms include

• The PC doesn’t always turn on the first time you try it.

• You find yourself pressing and holding the power button to keep the power supply engaged long enough to let the system start.

• The PC resets itself spontaneously.

• You hear a strained, grinding, or otherwise strange sound that seems to be coming from the power supply when it’s operating.

• You notice a strange drop in overall PC noise level that seems to resolve, only to happen again. This may mean the power supply stops and restarts, which it should not.

• You feel little or no air output from the power supply fan located behind a grill at the back of the PC.

• Devices directly connected to the power supply may seem to appear and disappear without signs of a device conflict or other problem. For example, a CD drive may disappear in Control Panel without any other reason, only to reappear again later.

  Warning 

  Don’t assume a power supply is dead until you make certain everything is properly and firmly connected and the PC has power available to it, yet the PC won’t turn on. If you suspect a dirty power supply fan and can see that it’s dirty, you’ll find instructions for cleaning the fan when we discuss fans in the section “PC Overheating: When Things Get Too Hot.”

Not all of these symptoms are only attributable to a dying power supply. Other problems, including operating system instability and a damaged motherboard, can, for example, cause a PC to reset itself spontaneously. A loose power switch can give you trouble when turning a PC on. But consider the status of the power supply when you notice these symptoms, especially when you notice two or more symptoms.

Tip 

If you experience any of these symptoms, or other symptoms you think may be related to your power supply, consider purchasing a replacement power supply before the old one fails. You can’t always buy the right power supply just anywhere; the wattage must be matched or exceeded and more importantly, the mount holes must align between the case and the power supply (meaning that you must buy the right power supply for the form factor for your system). If you bought your PC preassembled, check with your PC manufacturer to make certain you get the correct type. This information may also be available in your PC manual.

Evaluating Capacity

Many PC systems today ship with a 200-watt or 250-watt power supply, which is usually more than enough for the components installed into them. Where you begin to exceed a standard PC power supply is when you begin adding additional devices that consume a higher than average amount of wattage.

But how much wattage is enough? The rule of thumb with power supply capacity is that you need more wattage available than your connected PC hardware consumes. This means that if you’re running equipment that requires about 200 watts of power and your power supply is 200 watts, you’re hitting the power ceiling. In high-demand situations, some devices appear to fail temporarily because too many pieces of equipment are vying for power.

Table 11.1 lists some major PC components and the number of watts of power each device requires. While these are rough numbers that are based on available product information, they give you an idea of how these devices begin to cut into what sounded like a more-than-adequate power supply capacity. Notice that for many devices, these numbers are expressed as a range. Yes, many times these devices will only consume the number of watts represented by the low number of the range. However, you have to accommodate the possibility that each device might somehow hit the peak wattage demand at the same time. Then you must tack on a bit more working wattage room, both for safety’s sake and for the potential that you’ll add more equipment to your system, which in turn drives up your power requirements.

So if you’re barely skating by on a 200-watt power supply and you’re about to add a drive or two (say, a hard drive and a CD/DVD burner combination), you may want to upgrade to at least a 250-watt or preferably, a 300-watt power supply. That extra bump to 300 watts should buy you the power expansion room you need for the length of time you’re apt to operate your present PC.

Tip 

Should you go as high in power supply wattage as you possibly can if you decide to upgrade or replace? Not unless you anticipate adding a great deal of extra hardware. If you’re like many people, you may run out of room to add devices before you exhaust the capacity of a 300-watt power supply. While it’s true that a higher capacity power supply doesn’t always cost you more to operate in terms of power consumption, it can be overkill.

Table 11.1: PC Hardware Wattage Requirements

Device	Typical Wattage Required to Operate
CD drive (48x)	7–30 watts (Depends on the CD formats supported.)
CPU	18–50 watts (Depends on the CPU type and age; a Pentium III often takes 20–30 watts, while some Athlons require 40 watts or more.)
Fans	Variable; a case fan often needs 12 watts.
Floppy drive	4–5 watts
Hard drive (IDE/ATA)	5–20 watts per drive (Often, the higher the drive RPM, the higher the wattage used.)
Memory	10 watts per 128MB (some higher, some lower)
Motherboard (bare)	20–35 watts
Network adapter	4–5 watts
SCSI host adapter	20–30 watts
Sound (card) adapter (PCI)	5–20 watts
Video adapter (AGP)	18–35 watts
Video adapter (PCI)	4–15 watts

These are rough estimates; check the technical specifications for your devices, which are usually available in the product documentation.

Replacing a Power Supply

Before you decide to upgrade or replace a dead power supply, identify what you need. This involves

• Knowing the capacity you need.

• Knowing the form factor of your system. The form factor relates to the size of the motherboard and the type/shape and placement of the power supply. The form factor can usually be found printed on your existing power supply, in your computer or motherboard documentation, or by calling your manufacturer. Most systems today take some variation of the ATX form factor, but AT, LPX, and NLX form factors are also found.

• Verifying that the power supply is set to U.S. power settings. Many power supplies sold today are manufactured both for use in the U.S. (which uses a 115-volt standard) as well as for use in other parts of the world where a 230-volt setting is used. Most power supplies sold here are set for the U.S., but you occasionally get one that is set for 230 volts.

  Note 

  It can be tough to verify that a power supply is set to U.S. power standards. For this reason, purchase a power supply from a store or company that routinely sells them and that knows the products they sell. This tends to ensure that you’re getting what you expect. If you buy from a company outside the U.S., you increase the risk of getting a supply set for non-U.S. use.

Once you obtain your replacement power supply, verify that you got the correct unit. This information may be available in the accompanying paperwork, but verify it against the information available on the metal information plate on the power supply itself. This information should include the power supply’s manufacturer, wattage capacity, serial number, and other details.

Differences in Power Supply Quality

For most users, a power supply is pretty invisible; it’s secreted within the case. Users may be completely unaware of its rated capacity in watts. They also may not realize that there can be a big difference between the quality of one power supply vs. another. For example, if you were to compare two different makes of a 250-watt power supply, you might find that one is substantially heavier than the other. The lighter unit may have less power-handling hardware, such as fewer transformers, and may or may not be able to withstand what the heavier unit could. However, this isn’t the supermarket where you can easily compare cantaloupes; you generally won’t shop for a replacement power supply based on its weight. So understand that you may be doing more than saving money when you try to get a good deal on a power supply purchase; some of the missing hardware may result in a power supply more apt to fail under stress.

A decent quality, known brand with a good reputation and a warranty is generally all you need.

By default, most new PCs ship with an adequate-but-not-exceptional power supply unless you order a custom PC and specifically request a higher quality power supply.

Buying Refurbished Equipment

I can be something of a bargain junkie, as I bet many of you are. In a tight economy, it certainly makes sense to watch where you spend your money.

Frequently, and especially with devices I use occasionally but not all the time, I’ll consider purchasing a refurbished model of a product to save a bit of money. (If you’re not familiar with the term, a refurbished or reconditioned product may have been returned as defective, but it was tested, presumably fixed, and sold again with clear labeling indicating it’s not a brand-new product.) I’ve had excellent success with refurbished products, including PC expansion boards, peripheral devices like printers, cameras, and monitors, and consumer electronics such as video cameras.

But one place where I won’t cut corners is essential equipment like a PC power supply. While I’ve purchased refurbished power supplies in the past, I did so at a time when they were far more expensive than the average $20–$40 you spend for one today. One of these refurbished units I bought arrived at my door looking like it had been through a major catastrophe, while another arrived with such damage to its metal casing, I assumed an elephant had used it as a stepstool.

Sure, most of them worked well (I returned the other two), but this is one area where saving a few dollars makes little sense when you consider the importance of the device you’re buying.

What I do, however, is keep a working refurbished power supply on hand as a temporary solution if my main power supply fails. This way, I have something to fall back on to run my PC should it take a few days to get a replacement unit, but I don’t have to depend on the used power supply for any prolonged period of time.

Installing the Replacement

Since most of us will at some time need to replace a PC power supply and a dead power supply is a disaster all in itself, let’s walk through the steps of replacing one. But before you grab a screwdriver, do at least two things:

• Read the power supply instructions and read your PC documentation as it relates to replacing parts.

• Look at the current power supply (see Figure 11.1) and how it is currently connected

  
  Figure 11.1: PC power supply

Photo courtesy of Emily Sherrill Weadock

The trickiest part about replacing a power supply is simply making certain that you reconnect the new power supply up to everything the old power supply was connected to. If you don’t, you can have a serious problem with the replacement power supply or with another component that you might erroneously think is caused by a device failure.

First, get a roll of write-on tape or tiny sticky notes, along with a pen or marker. Use these to create labels for the connections to help you re-establish the proper connections later on. Then, with the power disconnected, the cover removed, and while wearing your anti-static wrist strap, take these steps:

1. Re-review the current setup.

2. As you note each power supply connection, place a piece of tape or sticky paper labeled with the connection’s identity on each connection on the old power supply. Make sure you note the orientation of the wide (typically white Molex) connectors that plug into the motherboard. Reversing these connections can damage the motherboard permanently.

3. Once complete, I unplug each connection between the power supply and the PC.

4. Using the screwdriver with one hand and using your other hand to balance the unit’s weight (especially important when you reach the last few screws), remove all the screws holding the power supply in place. Set the old power supply aside, but where you can still see it to review those connection labels.

5. Orient the new power supply so it’s positioned in the case exactly as the old one was. Screw it into place using the screws you removed from the old unit.

6. Using the labels on the old power supply as a guide, begin connecting the new power supply to the various components like your motherboard and your drives. Make sure all the connections are firm and secure.

7. Review your work and your documentation; adjust as necessary.

8. Leaving the cover off until you’re sure everything works, reconnect the power and start the PC.

   Warning 

   It’s not uncommon for a new component such as a power supply to emit a slight smell for the first several minutes to an hour after it’s pressed into service. But if you notice a strong smell that seems to increase in intensity or if you see smoke, turn off the PC and disconnect power immediately. Then contact the power supply manufacturer or the dealer/seller you purchased it from.

Home/Office Wiring and Other Appliances

Many old homes and office buildings may contain wiring that is not up to today’s electrical code. Obviously, you can have a problem with wiring last updated in 1940 or 1960 because in those days, there weren’t anywhere near the appliances or power demands that exist today. Overloaded wiring, as you already know, is a huge fire risk that too often becomes reality.

However (and considering the number of my friends who have purchased new or almost-new homes in the last year who immediately had to call an electrician to correct problems), not all modern-day wiring is an exercise in perfection either.

Nor do many of us, as electrical consumers, help. Rather than call in an electrician to add more outlets, some of us happily buy huge, honking power strips and set them up throughout our homes and offices. A room that was wired to allow plugs for 4–6 devices suddenly finds itself sporting plugs for 30. Repeat that in a number of rooms and, depending on the state of your wiring, you may overtax your resources and potentially increase your chances of fire. You may also be introducing a lot more dirtiness to your home or office’s power than was present before. Your PC won’t like that, and neither will your consumer electronics and appliances.

Tip 

Is there a working smoke detector in the area where your PC is located? If not, there should be. Unless the PC is located in an area where a false alarm could be tripped easily (around fireplace or kitchen smoke, for example), it’s wise to have a smoke detector positioned within 10 feet of the PC. Since PC smoke may not be voluminous unless more than a single component is involved, it may be harder for it to trigger the alarm from a distance. Remember to change the battery each year and test the unit regularly.

An electrician once described to me a simple test of overall building wiring. He said to spend a period of time (optimally as much as 3–6 months) during which you buy average (not cheap, not fancy) lightbulbs for your incandescent lamps, preferably during a time of the year when your area is prone to storms. Then chart how many lightbulbs you replace in your home during that period of time, especially where you have to replace the same lightbulb more than once in that period. If you notice that only one lamp seems to go through lightbulbs quickly, there may be a problem with either the lamp itself or the wiring in the outlet supplying the lamp with power. If instead, only lamps in a particular area of your house seem to need frequent lightbulb replacement, you’ve probably got a problem with wiring in a particular zone. For this, have your wiring professionally evaluated. However, he said, if you’re frequently replacing lightbulbs in various rooms throughout the building, get an electrician in there pronto (don’t wait for the rest of the test period to run out), and limit your use of electricity to serious need only until you do so.

If you need to call in an electrician, show this professional where your PC is located and ask whether he or she sees any potential problems with other devices being used on that zone. Large appliances such as refrigerators, freezers, and air conditioners tend to cycle; you may notice this in the form of flickering lights. In some cases, you have enough fluctuation in your power during such a cycling-up period that you can affect PC performance and the long-term health of your power supply (and other components, too).

What’s a zone? Unless you’re in a situation where you have just one or two rooms, your area is likely divided up into electrical zones. Each zone has circuit breakers or fuses assigned to it in your circuit or fuse box. If your zones are labeled, check this utility box to find the zone covering the area where your PC is located. You may be able to determine from that what zones cover your large appliances. If possible, avoid having your PC on the same circuit with your dishwasher, or other similar appliances.

Warning 

Never use a PC with an extension cord, especially not a common household, non-grounded extension cord.

Some Symptoms of Power Problems

If you’ve been on the planet for a few years, you may have noticed that electricity can do odd things all on its own, and when paired with your electronics, the list of potential problems gets even longer. However, there are some common symptoms that indicate you’re having power problems or that you’ve just suffered a power event:

• You walk away from your PC with it running and return to find it off, especially if the PC is off but other peripherals connected to it are still on.

• You experience what seems like a fast replacement rate on hardware components, having to replace memory or expansion cards more frequently than you might anticipate.

• You experience a hardware failure or malfunction after a major power event such as a power surge.

• Your PC or PC display misbehaves when a motorized device is used nearby.

• If you use a power strip to connect your PC, and you have to replace it more than once in two years.

• You turn on your surge protection device to turn on your PC and it fails.

• You notice a certain burning smell only when you turn the PC off.

The Best Methods for Troubleshooting Power Supplies

Statistically speaking, the PC power supply is the most often replaced component. Because of this, you always have to consider this possibility when you have a power-related problem that is affecting system operation or even the ability to turn the unit on.

One of the best ways to test a power supply is also one of the least pleasant. You need to have another PC that uses the same form factor of power supply, and you must remove the suspect power supply from the first PC. Then try installing it into the second PC (which also means temporarily removing its power supply) to see if you have the exact same problems. Obviously, this process is simpler if you have a spare power supply, as mentioned earlier in the discussion about refurbished equipment.

Another technique is to test to see whether you’re exceeded the capacity of your power supply. You do this by removing power connections to non-essential devices such as a second CD or DVD drive. If removing a few connections suddenly resolves your problems, the power supply could still be on its way to failing, with this test giving it a brief reprieve. However, it’s more likely that this test indicates you need a higher wattage power supply.

When you question whether interference or problems related to a non-PC device may be causing your power problems, unplug all non-essential devices or appliances in the room or zone where your PC is located. If the problem resolves, add back these other devices and appliances one at a time until you see the problem recur. This should identify the source of the problem, and you should move the other device or appliance to another electrical zone in your home or office.

If unplugging all the non-essential devices in the room doesn’t stop the problem, now unplug everything except the PC (and monitor). If it doesn’t improve then, check the PC itself for problems or call an electrician, especially if other devices in the room also show symptoms of interference.

Using PC Power Protection Devices

Now that I’ve scared you with dire predictions of electrical woes, let’s turn your attention to ways you can protect your system—and your ability to keep using it—from the very power it so desperately needs.

Power protection schemes and their associated hardware components exist at all places along the spectrum, from basic and inexpensive to advanced and costly. In fact, some of the protection equipment used by consumers today was largely only used in the corporate world less than a decade ago. But all computers need power protection. While you might be able to avoid a virus or dodge someone trying to access your computer remotely using good security practices, it’s hard to protect your hardware from power problems without buying a little more hardware.

Let’s talk about the two most common forms of power protection: surge suppressors and uninterruptible power supplies. Both of these are used in addition to your PC power supply. One special note about both devices: Surge protectors may need to be changed out after a major power event like a serious surge, while an uninterruptible power supply will need a new battery at least every few years. Build these tasks into your regular maintenance routine, but on an annual schedule.

Surge Protectors/Suppressors

If you don’t know what a surge suppressor is, you probably know it by another name, since it has many, including surge protector, spike arrester, spike suppressor, transient suppressor, and even lightning arrestor.

Warning 

A surge suppressor is sometimes called a lightning arrestor, but it really doesn’t protect from lightning, which can produce a much stronger voltage flow than most electrically based surges. You still need to have standard grounding (a lightning rod and/or a grounding wire) installed at your home or business. In addition, you still need to unplug your PC and its peripherals, including a phone line used for a modem, to protect them from power during a lightning storm.

More important than the name is the fact that many folks tend to confuse surge suppressors with power strips. They look alike, and both plug into a wall outlet and then allow other devices such as your PC, your monitor, and your printer, to be plugged into them. Both have a kill switch, allowing you to kill power quickly to the devices installed into it. However, I’ve seen many power strips without any true surge-suppression capabilities. This seems to be truer for the off-brand power strips sold at deep-discount stores.

What differentiates a surge suppressor is included hardware (a varactor diode) that tries to localize and minimize the damaging effects of a power surge. The varactor diode channels any voltage that exceeds the anticipated household 120 volts back into the wall outlet’s grounding wire, allowing the requisite 120 volts to keep flowing to your PC power supply. A decent surge suppressor is designed to die in the line of duty, if necessary, to keep your system from suffering the same fate.

You’ll find wide variations in the prices and features of surge suppressors, including the number of devices that can be plugged into it. Some manufacturers offer warranties that can offset your damage should the unit fail. Most of the price differential has to do with the level of protection the suppressor offers, although a suppressor by itself can’t protect you from every potential power mishap. It should, however, take the brunt of power fluctuations, providing a needed buffer between your PC and its power source.

Note 

While I believe you do get what you pay for with protection devices and that many of the more expensive devices are actually the better ones, I recommend that you have some protection, even if cheap, over none at all. A $7 clearance sale Curtis surge suppressor once burned itself out (literally, with just a bit of flames near the kill switch for heightened drama) to spare my testing PC from a mighty surge after a tornado touched down near my home.

Uninterruptible Power Supplies (UPSs)

An uninterruptible power supply (UPS) provides a battery power assist or backup to anything connected to it during times when your regular power isn’t available. Figure 11.2 illustrates a UPS manufactured by American Power Conversion.

Figure 11.2: An APC uninterruptible power supply

Photo courtesy of Emily Sherrill Weadock

Usually, the battery life provided by the UPS gives you a little extra time past the point of power failure in which you can finish and save your work and shut down the PC properly. This can avoid the effects of power-related crashes and lost work.

But don’t plan to work for a few hours into a total blackout; the battery life on these units is finite, and the more you have plugged into a UPS that’s installed between the power source and your PC, the shorter that grace period will be. Less expensive, less capacious units tend to give you a few minutes, while costlier ones allow you to work for 15 minutes or more.

Many makes and models of UPS come with warranties to offset your costs should your system be damaged while using the UPS, even the less expensive consumer ones that start at around $100. They also include some of the same protection hardware as surge suppressors.

There are two major types of UPSs:

Online  The most expensive type, it’s called online because it’s always operational even when your power is available and operating properly. This avoids any lapse of time during which the PC may be waiting for battery power to kick in.

Standby  Like the online type, a standby UPS monitors the power situation but it waits until it detects that power is unavailable before its battery power kicks in, which can lead to a slight (several millisecond) delay.

Note 

I experience far fewer problems and far fewer device failures on systems that I protect using a good surge protector coupled with a good UPS. I don’t think it’s a coincidence.