How to change a PC power supply


Dave’s Computer Repair Blog – How to change a PC power supply

Today’s blog post centers around one of the most important yet underrated PC components, the power supply. It doesn’t grab the headlines like a processor or graphics card and doesn’t have big numbers like RAM or an SSD, yet no computer can survive without one. Arguably the humble power supply, or PSU, is the most important component within your computer. Without it your computer is just a box that does nothing.

Your power supply takes power from the wall socket, cleans it up and breaks it down. It plays a vital role in maintaining a constant and accurate voltage suitable for delicate components and breaking high voltage down into low voltages suitable for electronics.

Like any component, power supplies can fail for a number of reasons and they will either cause errors such as blue screen of death in Windows due to voltage fluctuations or cut out completely. If you’re having issues with your PSU and don’t want the hassle of changing it yourself, bring it down to Dave’s Computer Repair in Hillsborough and we will be happy to do it for you.

Otherwise, here’s how to change one if yours stops working.

  1. Unplug your computer from the socket and remove the cable from the back.
  2. Take off the computer case and put to one side. The case will usually have thumb screws or crossheads and will likely slide or pull straight off. They differ by manufacturer.
  3. Before touching anything, take a picture of the inside of the case for reference. I tend to use my cellphone as it gets into small spaces and has a very good flash.
  4. Locate your PSU and follow each cable. There will likely be two to your motherboard and two to your graphics card (there might only be one to graphics depending on how old your computer is). There will also be one to each hard drive and DVD drive.
  5. Carefully remove the power cables from each. There is sometimes a clip holding them in place, so move the clip with your thumb and pull away gently until free.
  6. Unscrew the PSU from your computer case and slide it out.
  7. Get a replacement of the same wattage. There should be a label on the side of your PSU saying ‘300W’ or ‘500W’. Buy one of the same, or more wattage and as high efficiency as you can afford. Read this guide on PSU efficiency to learn more.
  8. Replace the PSU into the case and screw it into place.
  9. Replace each cable using the photograph you took. Make sure each hard drive and DVD drive is also plugged in.
  10. Double check all connections are in place and tight. Then check again just to make sure.
  11. Plug the mains cable into the back of the PSU and into the wall.
  12. Flip the switch on the back of the PSU into the on position and then switch the socket on.
  13. Watch and listen for any sparks or crackling.
  14. Turn the computer on and test.

That is all there is to replacing a power supply. If you would like to know more about choosing a PSU, this piece from is pretty good.