PSU does not turn on: why and how to fix it

Your computer can’t turn on if your PSU doesn’t turn on. It’s the unit that powers the rest of the computer to run, often adjusting the voltage as your computer’s needs dictate. However, even power supply units eventually fail and die. While there is a chance that your PSU can be recovered, PSUs that do not turn on often need to be replaced.

Why won’t my power supply turn on?

There are many reasons why your power supply won’t turn on. Most of them have to do with your incoming energy flow or how you are connected.

  • If your power supply is not getting enough power from the wall outlet, it may not be able to turn on. Even if one outlet works for another device, it may not provide enough for power supply.
  • Your cables could be damaged, interrupting the flow of power between the PSU and the wall outlet or the other components of the computer. You can’t always tell if a cable is bad just by looking at it.
  • The power supply may not be receiving a request for power from the computer. Specific models require a certain amount of charging before they start working.
  • The power supply could be broken and not working. In that case, you may want to exchange it for a new one. It’s a challenge to do actual repairs on the power supply because working with something with so many powerful capacitors can be dangerous for those without experience.

You are more likely to experience a problem with the wiring or connections in new construction. If you have had your power supply running for a long time, there is a higher chance that it will need to be replaced. However, you still need to work on it first to see if the problem is something you can quickly fix.

How to fix a power supply that won’t turn on?

Start by looking at the most obvious problems to see if they caused the problem. From there, you can start working on more complex solutions that may require more time or experience to use.

look for a switch

Many power supply units have a switch on the back that turns them on or off at the source. It is not the same as the power button on your computer. It’s on the back of the physical power supply itself.

Some people new to building their own computers or troubleshooting components don’t know the switch exists. So even if it seems silly, take a closer look at your power supply to see if it’s as simple as flipping a switch.

Try a different wall outlet


Another easy thing to check is the wall outlet and power strip, if you’re using one. They are sometimes damaged but still work well enough to appear functional. However, a power supply consumes a lot of power and may not be able to operate at a reduced capacity.

Try replacing the power strip and using a different outlet because it could be either. You already know where the problem is if the power supply works with the new connections.

check your plugs

First, you need to completely remove any of the power supply connections. The chance that something hasn’t been plugged in properly is high if the unit won’t turn on, especially if you’re working on a new build.

  1. Remove your power supply from the computer and disconnect any connections you use. You don’t want to leave anything plugged in.
  2. Examine each end of the cable where it connects and look for cracks, burns, or other signs of damage.
    damaged power chord
  3. Run your hands over the cable and look for unusual kinks in the line or other signs of damage.
    cable damage
  4. Look at the ports on the power supply and the other places that connect to it. Once again, try to find any signs of physical damage.

If you see damage to any part, it may need to be replaced. You can get replacement cables from the manufacturer of whatever component they came with, or find compatible cables at a tech store.

Check internal connections

Sometimes a power supply won’t turn on unless it’s actively sensing that power is actually needed. This is not true for all models, but it is for some. Therefore, it is essential to check if your connections are as they should be with the computer.

It is impossible to determine if your power supply requires a power load to turn on. You should check with your manufacturer if you think that is the problem, as they will be able to tell you if it is a possibility.


If you have not connected the front panel of the computer to the power supply and motherboard, you need to check and configure each connection. When you’re done, check the switches and plugs, then try turning on the machine.
Power switch

Many people have found that their PSUs weren’t working because the wiring required wasn’t quite right. If you have time, connecting your entire computer can give you good results, especially if it’s a new version and you haven’t done it yet.

The PSU manual can be of great help with this. You can explain everything that needs to be plugged in. Use it as a guide to make sure everything is assembled as the manufacturer recommends.

review your case


Sometimes a small problem with your setup can prevent the power supply from working. One user described finding a screw that fell out of one of its components and lodged under the motherboard. It prevented the motherboard from working properly, which means the power supply didn’t work on that particular version either.

If you find something out of place or damaged, try replacing it or using another one to see if the power supply turns on.

Try another power source


You can also connect another power supply to your computer, plug it in, and see if it boots. If it works, you know something is wrong with your main power supply. However, the computer that refuses to turn on with a power supply that you know is working is a sign that something else is wrong with the machine.

At this point, consider removing everything except one component that connects to the power supply. Try turning it on and see if it works. If not, turn off the power to that component and turn on the next one.

If the power supply turns on when something is connected but not when everything is connected, one of its components is bad and it affects the power supply. You can find out which one by continuing to connect components until you find the one that is not allowing the power supply to start.

What if I don’t have an armed computer or suspect something else?

If you’re just testing a power supply to see if it works and you don’t have a computer you want to change it to, you can try another way to tell if it works. However, only people who are comfortable with this type of electrical work should bypass a power supply to test it.

  1. Disconnect everything from the power source except the main AC cable and the 24-pin connector cable that it came with.
  2. Turn off the power supply with the switch on the unit. If it doesn’t have a button, you have to turn off the power strip or unplug it while you plug things in.power supply off
  3. Bend a paper clip into a U shape. It should be long enough to push each end into one of the 24-pin connector ports.
  4. Insert one leg of the clip into the PS_ON connector. It is usually the fourth pin from the left if the clip is on top of the connector cable while resting on a table. Some models have a visible green wire on the PS_ON connector.
  5. Insert the other end of the clip into a ground wire. Most PSUs have multiple ground wires, so you may need to check your manual to find the correct ones.
  6. Flip the switch. Look and listen to see if the power supply turns on. Remember: Not all PSU fans turn on right away, so you may need to watch and listen carefully to see if it works.

If the power supply turns on, it is functional and you can make it work. It means that the problem is more than just the drive itself.

How do I know when it’s time to buy a new power supply?

You should consider buying a new unit if your power supply won’t turn on and is out of warranty. Unfortunately, a power supply unit is not a part you want to mess around with because its failure could damage the entire computer. Once you’re sure it’s not something you can fix, it’s time to look for something new.

Buying a new power supply isn’t the most exciting part of buying a new computer, but it’s vital and you should think about which one to choose. Power supplies are sold with certifications, which means that they have a specific guarantee of their performance at different levels. Look for 80 PLUS certifications. They range from entry level to titanium, with each level being better than the last.

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