A power supply is what enables the computer to function. It is nothing less than the most crucial part. With a badly functioning power supply, a PC is just a heap of a receptacle of wires, cables, resistors, and plastic. On a desktop computer, the power supply is easily visible on the back of the machine. Follow the central processing unit’s power cable back to the source, and you will have found it. Immediately next to it you will find a fan, which is there to ensure that the power supply does not overheat the PC and cause irreparable damage to the machine.

Generally speaking, in the United States computers are powered by 120-volt AC power oscillating at 60 Hertz. Unfortunately, even today continuous voltage delivery is not guaranteed, and at times the power delivery to the power supply may be interrupted. For example, if the voltage suddenly rises beyond expectation (known as a voltage spike), or if it plummets even momentarily (referred to as the voltage sag), the sensitive power supply of the personal computer will most likely shut down. This also happens if the oscillation rate of the power is not the specified 60 Hertz. Last but by no means least, a power failure, such as what may be caused by a blown fuse, a power grid emergency, or just some naturally occurring event, such as a lightning storm, will interrupt the workings of the PC’s power supply.

Though the average computer user, who may just use the PC as a “toy” while playing computer games or as a tool communication to interact with others in chat-rooms or via e-mail, see a power interruption only as an annoying occurrence, the professional computer user views power interruptions with something like fear. For this very reason, personal computers are now also powered by alternate power supplies referred to as “uninterruptible power supplies.”

Uninterruptible power supplies (abbreviated as UPS) come in two important categories: the standby UPS and the continuous UPS. A standby UPS enables a personal computer to run by using electricity from the normal grid until it sees a problem. At this point the standby function alerts a power inverter and allows the personal computer to be powered from an internal battery -- which will, at some point lose its charge. A continuous UPS, on the contrary, is a self-contained, self-sufficient unit that operates under the same principle as the standby UPS, except that it recharges itself continuously.

Power supplies obviously tend to fail. The main weakness in their system is the cooling mechanism that relies on adequate air flow to perform its functions. In this age of DSL to allow users to stay continuously on-line, computers are not shut off as often as they used to be in the heyday of dial-up services. To add to this, many users’ aesthetical requirements of moving unsightly computer components as far to the wall as possible, and quite often hiding them behind curtains, table cloths, etc., it is not surprising that cooling is becoming a major problem. In addition to the this, extreme temperatures inside the home may add to a potentially disastrous outcome. Computer users better think through their power supplies’ needs before allocating a location for their CPU.

Always remember to place your central processing unit, which contains the power supply, in a place that does not suffer from extreme heat. Don’t ever cover up the back of the CPU with a heavy cloth, and always allow some room behind the unit for air to flow in and out without obstructions. If you get a slightly burnt smell, immediately shut down your system and unplug it from the electric point. If you use your PC for business or anything other than recreational activities, consider buying a continuous power supply to keep you up and running even if the power supply from the public grid gives trouble.