How to Know if Your Computer Power Supply (PSU) is Failing

Updated on January 25, 2016

Power Supplies Fail Sooner or Later

Much like hard drives in computers, all power supply units (or PSUs for short) eventually fail. Also like hard drives, it isn't a matter of if, it is a matter of when and why. In this article, you will learn how they fail, what some of the common symptoms are, and how to diagnose the problem.

An Apple Laptop PSU Might Look Like This
An Apple Laptop PSU Might Look Like This

So, What is a Power Supply Unit, Anyway?

Inside a computer, a PSU is the device that converts alternate electricity (the electricity from your outlet, normally 110V) to direct current to the components inside the case. Looking from the outside, it's the three-prong plug that plugs into your socket. Laptops' are much the same, except they're external: A block and cord that attaches to the back and plugs into the wall.

Every power supply is different. Some (typically for laptops) may have a low output of 65 watts, while others might output 1,000 watts or more. Some may only have 10 amps, while others output 65 amps.

When the PSU is no longer delivering the power your computer needs, things start getting wonky: See below for the signs.

A PC Laptop PSU Might Look Like This
A PC Laptop PSU Might Look Like This

Symptoms of a Failing Power Supply

More often than not, you just don't get any warning that the PSU is going to quit on you. However, sometimes it may do one (or more) of the following before it kicks the bucket:

  • Strange noises may emit from the back of the computer case where the cord is located.
  • When the computer is turned on, nothing happens. Sometimes this may coincide with a flashing light on the front of the computer or an indicator on the back of the PSU (if equipped).
  • The computer turns on for a couple of seconds and then turns right back off. While this can be a power supply issue, it may also indicate motherboard failures.
  • The computer is on for a while, but maybe while you're playing a game or using another application it just randomly turns off without warning. It might also display a blue screen of death.

When gaming is involved, one must realize that video cards these days require a lot of power and amperes to run correctly. When purchasing a PSU, be sure you have the wattage and amps needed for the equipment inside of your computer, especially the video cards.

The Blue Screen of Death May Indicate a Failing PSU
The Blue Screen of Death May Indicate a Failing PSU

So, Why Do PSUs Fail?

Power supplies just fail. Failures can be instigated by something you've done but sometimes, the unit simply gives up. Below is a list of common factors that send a unit to its grave.

  • Age: Most warranties last from 5-10 years, but that's no guarantee. Its life also depends on how often you use your computer.
  • Electric Interference (lightning, power spikes, etc.).
  • Dirt/Foreign Substance (cigarette smoke, house dust, etc.).
  • Brown-Outs: Intentional or unintentional drops in voltage. These load reductions are sometimes used in emergencies, like during a heat wave when everyone is using their A/C.
  • Overheating and/or Ventilation Failures.

The most common reasons are overheating and lightning. However, if you are a cigarette smoker or the computer is in a dusty environment, rest assured you will be replacing your PSU sooner rather than later.

A Desktop Computer PSU Might Look Like This
A Desktop Computer PSU Might Look Like This

Can Anything Be Done to Prolong the Life of a PSU?

Yes, there are a few things that will help you get the most out of a power supply. You should be able to extend its life beyond the manufacturer's warranty. Just remember that it isn't going to last forever.

  • Make sure you are not maxing out the wattage with the additional equipment you install. The power supply should exceed your system's requirements by a minimum of 20%.
  • Don't cheap out and purchase a junky unit. A nice one will cost a little more, but will go a long way.
  • Keep it as dust-free as possible.
  • Keep it, along with the rest of the computer, under 80 degrees.

Keeping the air quality clean may be difficult in some scenarios, so getting an air filter would be useful. Occasionally cleaning the system out will also prolong its life. The computer needs to breathe, or it will overheat and die.

Insten 20 / 24-pin Power Supply Tester for ATX / SATA / HDD, Black
Insten 20 / 24-pin Power Supply Tester for ATX / SATA / HDD, Black

This is the device I use to check the power supply. It's an inexpensive alternative to having a professional use the same device to check the PSU for you.


True Story

I was at a client's house to have a look at her computer. She said it wouldn't start. I had already assumed the PSU was bad, but I didn't expect to find even more when I arrived. It turned out the power supply had zapped every single component in the computer except a single DVD-ROM drive at the very top of the case. None of the components (motherboard, CPU, hard drive, etc.) had any signs of a surge such as burnt chips or even the smell of them being burnt.

In the end, the only other devices that powered up with the computer with a working PSU were the system case fans. I wasn't there when the power supply blew, but I would have to imagine that it released some sort of electromagnetic pulse through the whole system.

This was a weird case, and an educated guess as to what happened; however, there really isn't any other explanation. The hard drive wouldn't even spin. Only the devices that produce a natural electromagnetic current (fans) and the DVD drive (which was higher than the power supply) survived.

Lesson to be learned: Back up your data!

© 2009 Ryan Hutzel

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Submit a Comment

  • profile image

    ahmad abdulal 7 months ago

    I have just finished building my new pc and when i start it, everything goes on but i got nothing on the screen and all of the usb are not working. Can it be the psu?

    I tried to run my pc without any memory ram and i got no led from the motherboard that shows it need ram.


  • ryansccs profile image

    Ryan Hutzel 10 months ago from Greencaslte, PA


    It appears your fan speed is running slow, 2500 rpms is slow. 3-3500 is average. My thoughts would be to buy a better after market heatsink/fan that is rated for you CPU.

  • profile image

    Will 10 months ago

    My computer is running at 70-80C idle on the CPU and Motherboard.

    And baciscally everyone on Reddit recommended to re-apply my thermal paste, which I have done and there isn't any change in temperature. Please Help.

  • ryansccs profile image

    Ryan Hutzel 11 months ago from Greencaslte, PA

    The loud pop is most often a capacitor blowing out. Capacitors are located on almost all circuit boards. Look generally on the motherboard, video card, and or psu. It could be a PSU issue, however not exclusively.

  • profile image

    Brian 11 months ago

    Was playing a game on my PC when I heard a loud pop and now won't even turn on could this be a psu issue?

  • profile image

    YOUDIEMOFO 19 months ago

    Electromagnetic Pulse went through the whole computer eh....?!?

    Now I think I have heard it all....

  • profile image

    Trollinjaflex 2 years ago

    What if my PC was making electric shocks ,does this mean my psu is failing

  • profile image

    Firehawk4nzzz 2 years ago

    ryansccs...thank you, i am truly grateful, i was under the impression it was only using 50 watts, i don't even know why, but thats what i thought...thank you, sure this means I will need a new psu, but thanks to you i can at least identify the problem, really i can't thank you enough for responding so quickly...thank you!

  • ryansccs profile image

    Ryan Hutzel 2 years ago from Greencaslte, PA

    @Firehawk4nzzz, The GTX 750 requires 400w minimum with 20amps on 12v rail for PSU. Get a new power supply, you are under wattage. At this point it is very possible you are simply "brownout" your system. To much amperage needed, not enough wattage either.

  • profile image

    Firehawk4nzzz 2 years ago

    ok so my specs for my pc are:

    Mobo: GA-F2A78M-HD2

    Ram: Kingston hyperx fury 1600 ddr3

    cpu: AMD A10-6800K APU 4.1 Ghz

    gpu: gtx 750 from msi, It was referbished by newegg when i got it if that helps

    and psu: logysis 330 watt (not sure what the brand name is but it came with the case i have

    anyway, i've ruled out the gpu, and i've switched the ram in the whole 2 slots on my mobo, this seemingly did nothing, so either my motherboards ram slots are both broken or none of them are broken, i'm inclined to choose the later

    I ran memtest86, this told me no errors were found with the ram it'self, so im left with the psu, or the cpu

    I have no idea how to test for it being a cpu issue...although i'm not even entirely sure it's possible to have a cpu error and still boot the computer at all, but iv'e been wrong before.

    This leaves me with a PSU problem...or something else i've overlooked...

    at some point soon i will switch out the psu for a 1000 watt for testing purposes, if it fixes the problem, or for that matter if it doesn't ill make sure to report my findings here.

  • ryansccs profile image

    Ryan Hutzel 2 years ago from Greencaslte, PA

    @Firehawk4nzz, Have you ran memory check for the memory itself... I would be weary of this being the PSU, but you also did not list everything that is in your computer and what PSU wattage and amperage you are running either.

  • profile image

    Firehawk4nzz 2 years ago

    Ok so...I hope you guys can confirm weather or not this is the case, but for a few weeks now my computer has been randomly turning off, or BSOD, just crash, reboot, repeat.

    However when it does crash, when it reboots the memory is cut in half. I have 1 stick of 8GB, and when my pc reboots it only says 4 is available

    ...originally i thought it was a cooling issue, but my temps average around 35 degrees so, thats not it, then i checked that maybe the gpu was the problem, so I uninstalled that, and ran of the integrated gpu on my mobo, that seemily showed no improvement, as my computer still crashed, and memory isn't the problem because if it was, the pc shouldn't boot at all, much less at full capacity to begin with.

    (I'd like to clerify that, booting fresh, allows the full ram to load up, although just recently the pc crashes before it can even boot's quite infuriating)

    A buddy from work says he had the same problem and bought a new more powerful psu(1000 watt), and that solved his problem.

    I'm running the normal components of my pc and a gtx 750 off of a 330 watt psu, according to the specs, the whole build should only be using 250 ish and this just started happening recently this the sign of a failing psu?

  • profile image

    Martin Caldera 2 years ago

    Hi friends, There are 3 simpthoms that tells you, that your PSU is about to die:

    1.-Your Pc screen shows BSODs.

    2.-Your DVD burner opens slow or do not opens.

    3.-It tries but won´t boot properly.

    4.-Your HDD makes strange sounds, in this case you unplug the DVD burner, and if it boots properly with no weird sounds from HDD, you can sure tell its the bad PSU.

    Once you´ve changed your bad PSU, all three disappear for good.

    Sorry for the grammar.

  • profile image

    Adam 2 years ago

    So I'm trying to figure out why my HDDs keep dying. My symptoms came slowly. At first the graphics began bugging out while playing games (I suspect it's due to my power-hungry GPU) and my HDD made a noise every now and then. It slowly got worse and worse until the computer began freezing and forcefully rebooting. Soon thereafter, It froze during a game, turned off, and reported hard drive failure upon reboot.

    I assumed at first it was HDD failure alone and replaces it, only to have failure a week later. The exact same symptoms as before, only much more rapidly. At that point I thought there may be an underlying cause.

    The bugginess of the graphics during games around the time of failure lead me to suspect the GPU was hogging power away from other components. The HDD probably wrote corrupt data from a lack of voltage.

    I can't test the PSU under load because without a drive, I can't run the GPU. Is it possible for a power supply to be partially dead and provide less power than it was built for? Or is there another issue?

  • profile image

    gameguru 6 years ago

    How do I tell if it is a junky PSU?

    Read reviews and find out how much power your system will use or find a PSU calculator, then find a reputable supplier and check the specifications on the PSU you want to buy or buy a PSU from a dedicated company in the power supply market, generally most top manufacturers make good power supplies and it is only high end enthusiasts and gamers who are concerned with figures of how one supply slightly excels another, for standard PC use you don't need to be concerned too much over numbers unless overclocking or fine tuning for high end use, gameguru.

  • profile image

    TGWOH 8 years ago

    Stumbled on this article. Devoured it with glee. Thanks.

    My 3.3 volt rail is low (2.8v). I will replace the 300 watt PSU. I shop locally and online. Everyone selling them says what they sell is not junk.

    PSUs on the shelf 2 years ago cost $75. Now those same PSUs cost $20 with the same warranties ranging from 6 months to 2 years.Most then and now are made in China and meet US certifications.

    So how do I tell if it is a junky PSU?

  • LondonGirl profile image

    LondonGirl 9 years ago from London

    very helpful, thanks

  • katyzzz profile image

    katyzzz 9 years ago from Sydney, Australia

    Interesting information, keep on informing us.