Signs and Symptoms of a Dying Power Supply

When hardware begins to go wrong in a computer, it can be a highly stressful situation. Not only is there the concern that your computer is dying, but with so many options as to what it could be, it can be hard to diagnose which part is malfunctioning. The power supply, being the source of energy for your entire system, can cause major issues should it begin to go wrong. But what can you expect to see should your power supply go bad?

The Symptoms

Computer Won’t Start at All


Given how the power supply is the central hub for all your computer’s energy, it makes sense that if it has died, the computer will fail to start. What makes this tricky, however, is that a “dead” computer doesn’t always mean there’s a problem with the power supply. It could also be an issue with the motherboard or the power cable, for instance. As such, while not a surefire way to diagnose a faulty power supply, keep it in mind should this happen to you.

Computer Randomly Shuts Down or Restarts

You might find that your PC shuts down during boot-up or use. Be extra wary of the power supply if it occurs during moments of high stress, such as video encoding or gaming. This may be due to the power supply failing to keep up with the demands of the computer. However, this is also a symptom of an overheating processor, so make sure the heat sink is kept dust-free and the processor is running cool before pinning blame on the power supply.

Random Blue Screens and Computer Crashes


Akin to the above topic, a power supply going bad can result in a blue screen, or a “hard” computer freeze. Unfortunately, crashes are one of the broader areas of computer problems. A lot of of computer hardware and software drivers can cause a blue screen, and a few of them can cause hard freezes too. If you’re getting computer crashes, don’t suspect the power supply immediately, but keep it in mind as you test to see what’s going wrong.

Power Supply Fans Make a “Grinding” Sound

When a fan within a computer starts to go bad, it makes a very distinct and identifiable grinding noise. This is a sign that the fan’s bearings are coming to an end. Even if the grinding sound goes away by itself, the fan may be coming to its end.


If your computer begins making this grinding sound, it’s usually very sudden and without warning. When it happens, try to identify what component the grinding is coming from. If it’s from the power supply’s fan, you’ll want to get it fixed before it dies and causes the unit to overheat

Obvious Signs of Trouble

When a power supply unit goes very bad, it might begin to expel smoke or emit a burning smell. This is a very real sign that it needs to be replaced immediately! Turn off the PC and don’t use it again until you’ve replaced the unit.

What Now?

So you suspect, or know, that your power supply is to blame. Where do you go from here?

Is the Wattage Sufficient?


Power supplies have a limit to the amount of power they can produce, represented by their wattage. If the computer is drawing more energy than the power supply can keep up with (either because you’ve built a new computer, or you’ve added new hardware to an existing one without upgrading the power supply), it’ll cause problems with power distribution. Check your power supply’s wattage against how much your system needs by using a calculator, and make sure it’s properly covered. If it’s not, consider upgrading your power supply to a more powerful unit.

Check the Power Supply

If you suspect the power supply is going wrong but don’t have concrete evidence just yet, there are ways to check it. You can download software such as Open Hardware Monitor or Speedfan to check the voltages of the power supply. Look at the computer’s values for the 3.3V, 5V and 12V entries. If your voltages are 5% over or under those numbers (for example, your 5V value is below 4.75v or above 5.25V), something’s not right with the power.


There are relatively inexpensive gadgets called power supply testers. The idea is that you plug the power supply into it, turn it on, and the tester will tell you if anything is wrong. Make sure you purchase a well-reviewed and trusted tester if you go this route. Inaccurate or confusing testers will only make things worse!

If you feel like a bit of an electrician, you can test the outputs yourself using a multimeter to get readings from the power supply’s output. However, this takes advanced knowledge of how a power supply works, as well as how to obtain the readings. Only use a multimeter if you’re confident in your abilities to use it correctly!

Replace the Power Supply

If you can confirm the power supply is going bad (such as a noisy fan within it), then getting a replacement is ideal. Note the amount of wattage your old power supply is (usually on its specification sticker), then purchase a new one with the same or higher amount.

Seek Professional Aid

If all else fails, take the computer to a trusted repair shop and let them know the symptoms. A good repair shop will be able to check the power supply and advise you depending on the result.

More Power to You

When a hardware fault begins to cause havoc on your PC, it can be hard to tell what is causing all the issues. With a few symptom checks and tools, you can better diagnose your problems and work out whether the power supply is at fault.

Have you ever had to deal with a bad power supply before? Tell your stories below!

Image credit: Blue screen of death xp ati, Chocolate Horlicks (Own work)

Simon Batt
Simon Batt

Simon Batt is a Computer Science graduate with a passion for cybersecurity.

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