1: Un expected shut down of your computer.

2: The monitor is beeping.

3: Monitor is not opening.

4: CPU is opening but the monitor display this note: One of the hardware is not function well.

Troubleshooting a problem with a PC can be very difficult and frustrating. Fortunately, there are places to turn for assistance, and there are also tools at your disposal that can make the job much easier. These can be used to identify specific problems within the PC, or just give you more information about the system so you understand better what you are dealing with. This chapter takes a brief look at these tools, which can make your life easier if you are having trouble.

Here are some common software diagnostic tools that you will want to consider including as part of your troubleshooting arsenal:

• Power-On Self Test (POST): I am cheating a bit here because this isn't a separate diagnostic utility; it is in fact built into your system BIOS and it runs every time you start up your PC automatically. It is often the best indicator of system problems; make sure you pay attention to its audio and video messages. Don't disable its error-reporting functions unless you really need to.
• MEM.EXE: This simple utility, built into recent versions of DOS and also Windows 95, provides you with details about your memory configuration, as well as what is currently using your memory. It is especially useful when run with the "/C" parameter (use the "/P" parameter as well to make the output pause when it is scrolling).
• Microsoft Diagnostics: Better known as "MSD.EXE", this is a small DOS utility that takes a brief inventory of the contents of your PC and shows them to you in a text-based format. This is very useful for seeing what disks are in the system, how much memory is installed, and also for checking system resource usage such as LPT ports and IRQs. It will show you what type of BIOS you are using and also what UART chip you have in your serial ports. MSD.EXE is included in later versions of DOS.

Computer hardware

Power supply

Power is supplied to your computer in two stages. First, power is conveyed to the case from your electrical utility to your wall, and through the black power cord to the PC. Then, the internal power supply transforms this standard household electricity into the forms that your computer needs. Most people take electrical power for granted and don't think too much about it. This is also true of the internal power supply, which is usually just considered part of the case and given little attention. (The power supply is not part of the case!) The power from the utility itself is taken for granted and rarely given a second thought--that is, until disaster strikes. It is my hope that by taking the time to explain in more detail how electricity works and how it powers your PC, this subject will be given more attention in the future.

External Power

The matter of power begins with a look at the power delivered to the case. The power that comes into your home is normally quite reliable, but it can be surprising how many quality problems it often has. Spikes, surges, blackouts, brownouts, line noise-all are common power problems that you don't generally notice (well, you notice a blackout :^) ). Usually, the electrical devices you use manage to deal with them (at least, most of them.) Your computer's power supply has some tolerance to these problems as well; the more expensive the system, the more the power supply can tolerate without failure. If your power supply is inexpensive, however (and too many of them these days are) then poor power can lead directly to system troubles that manifest themselves in ways that would never lead you to suspect power as the cause. Taking some steps to improve the quality of the power going into the system can help prevent problems no matter what PC you use.

Electrical Power Basics

There are many PC users who don't know a lot about electricity or power at all. There's nothing wrong with this. I drive my car every day and have very little understanding of how anything inside it works; this is, to some extent, just the way our society is today. At the same time, though, if you really want to understand your PC's power issues, you have to have at least a basic understanding of electricity, how it works, its different types, and its fundamental characteristics.

Thick, heavy text books have been written on electrical power. I'm obviously not going to duplicate them here in a few pages. Nor, I would add, do I need to. The intent here is to help you, the PC enthusiast, learn enough about power to help you understand how PC power supplies and power protection equipment operate.

External Power Problems

There are several types of problems that your computer's internal power supply will be subjected to if you choose to plug the computer right into the wall. Some are minor problems that your system may be able to deal with, while others can cause data loss or even permanent damage to your PC. In the section on electrical basics, we showed what ideal sinusoidal AC electricity looks like. Unfortunately, that's not what really comes out of the wall in the real world.

In this section we take a look at some of the common problems that plague conventional utility power.

Line Noise

Line noise consists of small variations in the voltage level delivered to the computer. A certain amount of line noise is normal (no power generation circuits are perfect) and for the most part, all but the absolutely cheesiest power supplies will deal with them without difficulty. However, in some areas the power quality is worse than others. Also, if the PC is sharing a circuit or is physically located near devices that cause electromagnetic interference (motors, heavy machinery, radio transmitters, etc.) then line noise can be a serious concern. Noise that the power supply cannot handle can cause it to malfunction and pass the problem on to your motherboard or other internal devices.