Inside your computer is a component that is the lifeblood of your hardware system. It is responsible for your motherboard, your hard drives, your CD and DVD drives, and a half-dozen other possible components. For many people, the only part they see is this important component – the power supply – is the rear where they plug in the power cord from the wall.

The power supplies job looks simple: to convert alternating current (A / C) to direct current (D / C) which, like most electronic devices, is what your computer uses. Inside the computer case, various wires and plugs are attached coming out of the power supply. These are attached to the different components inside the computer. Some higher-end power supplies from OCZ, CoolMax, and Ultra allow you to only attach the wires and plugs you need. This can create less clutter inside the case and help to improve air flow which keeps your computer running cooler.

Sadly, many computer manufacturers include power supplies that are cheaply made and have very minimal power capabilities. A power supply is measured primarily in terms of watts. Finding out how many watts a power supply can generate is the first way to determine if your computer system is risking being underpowered.

Even today, some systems are still shipping with 150 watt power supplies. This is strictly acceptable. A basic system should have, at the least, 350 watts of power capability. Many systems have 500 watts or more of power available, and some high-end gaming systems are being fitted with 1000 watt power supplies.

The number of components that might be running at once determines how much power you need. Your motherboard consumes more power when you are running processor-intensive tasks such as games, 3-D modeling or graphics, and multimedia applications. You might have your hard drive and your DVD player going at the same time. But, of course, the most pressing need for a new power supply is after an upgrade. Adding a second hard-drive, more memory, or a newer motherboard are all excellent reasons to upgrade your power supply.

When buying a new power supply, take the time to determine your long-range plans for your computer system. Do not buy just enough power for the moment. Buy enough for future upgrades as well. You can not really go wrong with too much power. But do not buy a power supply that far exceeds your realistic expectations; you'll just be wasting electricity.

For a fancier look, some power supplies now have clear cases, colored lighting, or interesting metals. If you have a computer case that is clear, these units can add a little flair to an awkward dull looking part of your machine. Look for these designs from power supply companies like Apevia, Ultra, Xion, and Diablo.

Although you can buy generic power supplies, many of them may not be reputable. It is not unheard of to have a power supply fail – and take a motherboard or hard drive with it. Buy a quality unit. Power supply companies now brand their products, offer warranties, and are creating units that run cooler and quiter than their predecessors. Bargain units are not always a bargain.