How To Test A Computer Power Supply

If you are having suspected power supply issues with your computer, don’t bring it to an expensive shop just yet. You can test the power supply on your computer on your own, and it is actually not that hard. Let’s go through a step by step process on how to test your computer power supply.


Testing A Computer Power Supply: Step by Step

Now, if you are not into technical details too much, and would rather just be playing your games, we have an easy way for you to test your computer power supply. Yes, the power supply could be the issue your computer is having. Will it not turn on? Will some of the functions not work? Does your computer turn off during an intense game? Well, if so, you might have a power supply issue. Let’s go through a very simple step by step process you can follow to test your computer power supply by yourself. It might sound complicated, but these steps will make it about as easy as can be, so let’s get right to it!

  1. The first thing that you want to do is to turn on your computer. If it is already on, turn it off. In other words, this step involves testing if the power is actually on. Make sure that all of the power cables are properly connected and that the power switch (the little switch with a line and a circle) is in the on position. If you are still experiencing problems even though the power switch is on and everything is well connected, unplug all power sources and move on to step two.


  1. Now that you have confirmed that there is an issue not involving the exterior cords, unplug everything and open up the case of the computer. Use the appropriate tools to unscrew the side of the computer case to get to the inside of it. Now you should follow all of the cables from one end to the other, from the outside to the inside, in order to make sure that all cables in relation to the computer’s power supply are actually connected. If a connection is not the issue, unplug everything and make sure it is properly unplugged. Be sure to note where everything was plugged in, or else you will have a hard time when it comes time to put everything back together.


  1. Now you need to make a little testing device, which can be done with nothing more than a simple paper clip. Take the paper clip, unfold it, and then make it into a “U” shape. You can use this paper clip to trick the computer into thinking that it has been switched on, when in fact it has not. This is because the paper clip acts like those little pins when the power supply is plugged in.


  1. Now you need to find the 20/24 pin connecter. It is usually the largest connecter for the power supply and will also be attached to the motherboard of your computer. You now need to find the green pin and the black pin. They will usually be pin numbers 15 and 16 on the 20/24 connecter. Once again, make sure that all power sources are off and disconnected. You don’t want to barbeque yourself here. Insert one end of the paper clip into the green connecter and the other into the black connecter. With the paperclip inserted into the right connecters, put the cable somewhere where it will not be disturbed.


  1. Plug in the power supply and flip the power switch on the rear of your computer into the ON position. If the power supply is working, at the very least, the cooling fan in your computer should turn on. If the fan does not turn on, make sure the paperclip is plugged into the right pin holes, reconnect the power, and try again. If the fan still does not work, the power supply is probably broken. To be clear, this test will not tell you if the power supply is working on point, but it will let you know if it turns on at the very least.


  1. Now you need to check the output. If your computer turns on and is working, try using diagnostic software to see what the power supply output is like. If the computer does not work and you cannot run diagnostic software, just move on to the next step on the list.


  1. Shut the computer down and unplug the power supply. Open up your computer just like before and disconnect all cables and components from the power supply. Make sure everything has been properly disconnected before moving on to the next step.


  1. Get yourself a power testing unit. You will need it here. You need to find the 20/24 pin connecter on the power supply, just like before. Connect the tester to the pins. Now, plug in the power supply and turn it on. The tester should light up automatically if the power supply is working.
  1. You need to look for four essential voltages, these being +3.3 VDC, +5 VDC, +12 VDC, and -12 VDC. All of these need to be within +/5% of the accepted range, with the -12 VDC being able to handle up to +/-10% of the normal rate. If any of these are outside of the accepted range, you have a bad power supply. You also need to test each connecter cable separately to see if they are working.


  1. You can also use a multimeter to test the power supply. Make sure to connect one pin to the black pin connecter for grounding and the other to the one you are looking to test. Make sure to have a voltage chart with you to compare the actual output to the required output. If any of the voltage levels fall outside of the threshold, you have a bad power supply.

If you are still having issues after all of this, you might just need to get a new power supply or bring your computer to a professional for further tests and advice.

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