The power supply. It's arguably the most important component in your computer; without power, none of the other parts will work, no matter how great they are. The main purpose of the power supply is to convert electricity from alternating current (AC), which can travel farther and retain its strength, to direct current (DC), which can’t travel as far and is safer than AC power. Every machine has a different power requirement based on the energy consumption of its components, and therefore, there are a million different power supply units (PSUs) made to meet all these different demands. Not only are there PSUs for different demands, but there are even different ratings based on a given power supply’s energy efficiency.

Step 1: 80 Plus Ratings

These are known as 80 Plus ratings, a certification made to ensure a power supply has more than 80% efficiency at 20%, 50%, and 100% of the energy load it’s rated for. There are 6 different ratings: 80 Plus, 80 Plus Bronze, 80 Plus Silver, 80 Plus Gold, 80 Plus Platinum, and 80 Plus Titanium. These standards increase in efficiency based on the rating, so for example, 80 Plus Silver certified power supplies run at 85% efficiency at 20% load, 88% at 50% load, and 85% at 100% load.

Image Source: Wikimedia Commons

Step 2: Parts of a PSU

There are quite a few different parts that allow a power supply to work as well as they do, so I took apart the PSU from an old computer of mine and labeled some of the more important parts.

Transformer: The transformer performs the power supply’s primary function of translating that AC power into DC power.

Heatsink: A power supply can get very hot, and therefore requires a heatsink, sometimes multiple, in order to keep cool.

Wires: These are pretty easy to identify and figure out the purpose of. They connect the power supply to all the different components on the motherboard, but it is important to mention that there are multiple different groups of wires which connect in different places, including the typical 24 pin connector.

Electrolytic Capacitors: These are pretty important, they help remove unwanted frequencies that would otherwise interfere badly with the power supply.

The unlabeled red box points out the location where the cord is plugged in, so you can see

Dust: This is not a component, but I would like to use this opportunity to mention how important it is that you regularly clean dust from EVERY part of your computer!

Step 3: Maintenance and Troubleshooting

Cleaning off dust is just one of the ways you can keep your power supply in good working order, though. Perhaps the most important tip that can be offered is to always make sure you have your power supply plugged into a surge protector. One of the more common ways a PSU can be damaged is through excess electrical current resulting from a power surge, and a surge protector stops that before harm can be done.

The most obvious way a faulty power supply manifests itself is through your computer simply not powering on, but this is not the only way things can go awry. Its effectiveness may diminish under load, and your computer can become unstable if the proper amount of power can’t get where it has to go. It is also sometimes an issue when a new component is added to your machine, your power supply may no longer be able to supply the proper voltage, so it’s important you always check to make sure!

A good tool to use to check a power supply is a digital multimeter. These can tell you the voltages of individual wires, allowing you to discern whether or not something is getting the proper voltages. Keep in mind that there are supposed to be different voltages for different colored wires, and these are standard throughout power supplies. To test what voltage is being output by a particular wire, touch the tip of one of the two test leads to the base of a black wire. This keeps you grounded, so excess electrical current cannot harm you or your machine. Once you are grounded, touch the other test lead to the base of another wire. The voltage of the wire will show up on the multimeter, and you can compare it to the standard to see if it is correct. It sometimes happens that it isn’t precisely correct, but that doesn’t necessarily mean something is wrong.

In the case that something is wrong, in most cases the best option is to simply replace the broken power supply. Often times it ends up it might be more expensive to have it repaired or repair it yourself than it is to get a replacement, and there is always the possibility it could be damaged further in a repair attempt.