Technology Explained

The Effects Power Outages Can Have On Your Computer

Joel Lee 11-09-2014

Do you unplug your computer during severe storms? If not, you may want to start.


It’s long been known that frequent electrical storms and power outages can damage electronic devices or full-out destroy them, and that includes computers. Anyone who claims otherwise is lying or misguided. The worst part is that power outages aren’t the only concern.

What are the risks of electrical failure? How do they impact your computer? And what can you do to protect your computer from being fried?

The Different Types of Electrical Anomalies

The electricity flowing through your home is not constant. Ideally it would be, but the reality is that electrical currents can ebb and flow, sometimes dropping in voltage and other times surging with extra power. All of these can have undesirable effects.

When power completely shuts off, it’s known as a blackout. These tend to occur due to issues beyond your control (e.g., power station disruptions, damaged electrical lines, etc.) but sometimes they can be self-inflicted (e.g., by shorting or overloading circuits).


And then there’s a similar issue called brownout, which is when your electrical voltage experiences a temporary drop without fully blacking out. If you’ve ever seen your lights dim for unknown reasons, it was probably due to a brownout. Brownouts can be intentional as a way to reduce electrical loads How Much Power Is Your PC Using? Computer power consumption can be estimated. Most of the components inside a PC have specific minimum and maximum power draw figures and, because quality control is so tight, it’s rare of a part to break... Read More and prevent blackouts, though they can be unintentional as well.

On the other side of the spectrum, we’ve got the power surge, which is when an appliance receives more electricity than intended for at least three nanoseconds. Surges can be caused by a number of factors, including short circuits and electrical line malfunctions. If the increased voltage only lasts one or two nanoseconds, it’s a power spike, which is most commonly caused by lighting.

Why Blackouts and Surges Are Dangerous

The real danger of blackouts and brownouts is the unexpected computer shutdown. Operating systems are complex and they must go through a “shutdown sequence” to make sure all running processes have correctly terminated before powering off. A sudden loss of electricity can interrupt important threads and leave your computer in an inoperable state.

System files are the largest concern. Consider what happens when a hard drive is writing data to the disk but suddenly shuts down in the middle of it. Suppose the file being written was a system file necessary for the booting process? Now that file is corrupted and you can’t boot up your computer without going through an involved recovery procedure How To Resolve Windows 8 Boot Issues Windows 8 uses a new "hybrid boot" feature to improve boot times. When you shut down, your computer doesn't actually shut down normally - it performs a sort of limited "hibernate" that stores a state... Read More .

Furthermore, frequent power outages can reduce a hard drive’s physical lifespan. The read-and-write head, which hovers over the spinning platters during operation, snaps back into its original position upon power loss. This sudden movement can cause tiny imperfections that accumulate over time, increasing the likelihood of a “head crash”: a malfunction that occurs when the head touches and scrapes the platter surfaces, effectively destroying the hard drive.

Solid-state drives How Do Solid-State Drives Work? In this article, you'll learn exactly what SSDs are, how SSDs actually work and operate, why SSDs are so useful, and the one major downside to SSDs. Read More can also suffer catastrophic damage from sudden power cuts. Issues can range anywhere from data corruption to total malfunction.

It should be noted that although power outages will not cause direct harm to computer hardware other than data drives, it’s possible for power outages to be accompanied by power surges, which can cause severe damage to hardware.


As far as power surges and spikes are concerned, your biggest worry should be lightning. Most homes are built with electricity lines that deliver somewhere around 120 volts. The current of a lightning strike, however, can exceed several million volts. That’s like trying to fit the flow of Niagara Falls through a straw.

Electronic devices aren’t designed to withstand that kind of influx and if the power of a lightning strike ever surges through your lines, you can be sure that any unprotected device will be fried beyond repair.

The next time you decide to use your computer during a storm, don’t be surprised if a spike hits and you have to say goodbye. It’s more common than you think.

Protecting Against Power Outages

The only foolproof way to protect your computer against electrical anomalies is to unplug it completely until the danger has passed. Seriously, it has to be physically disconnected. Flipping your power switch to “off” isn’t going to cut it. This is the only method of protection with a 100 percent success rate against power outages and power surges.

That being said, some of us are probably going to ignore the storm and stay plugged in regardless. It wouldn’t be the smartest move, but definitely understandable. In that case, there are two semi-effective alternative methods.


Against power surges, you’ll want a surge protector. This apparatus, which looks like a bulkier version of a power strip (the two are not the same), will attempt to divert electrical surges away from the devices plugged into it. Surge protectors are rated to withstand a certain maximum voltage and once they’re triggered, they must be replaced.

If you need help picking one, we have a guide to buying surge protectors Are Surge Protectors Necessary? Here's What They Really Do A surge protector is not the same thing as a power strip! Here's how they're different and why you need a reliable surge protector. Read More . Note: No surge protector will protect you against lightning strikes!


Against power outages, you’ll want an uninterruptible power supply. This apparatus contains a backup battery that will continue to provide power to your computer even when your power goes out. Most UPS devices only last a few minutes, but that should be enough time for you to issue a proper shutdown.

UPS devices can also come equipped with surge-protected outlets, making them more of a two-for-one purchase and offering more value per dollar. If you live in a building or location that frequently experiences outages, surges, or both, a UPS will be a strong investment.

Sudden changes in electrical voltage can cause real damage to your system and/or your hardware. Don’t fall into the trap of thinking it would never happen to you. Protect yourself early, protect yourself adequately, and don’t forget to back up your data!

If you need help picking an uninterruptible power supply, read our guide to buying a UPS and our roundup of the best UPS units you can buy The 6 Best UPS Units You Can Buy Right Now An uninterruptible power supply is key for emergency backup power at home. Here are the best UPS units available today. Read More .

Image Credit: Flashlight Via Shutterstock, Lightning Strike Via Shutterstock, Surge Protector Via Shutterstock

Explore more about: Computer Maintenance, UPS.

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  1. BODHI
    September 12, 2018 at 6:09 pm

    see next. Through this, we also become modest and realize how small the places we live in are.

  2. oksidarma
    November 13, 2017 at 5:46 am


  3. faith
    July 11, 2017 at 7:54 pm

    somedays electric cutting computer running during. solution what's?

  4. Sanchita
    January 11, 2017 at 2:24 pm

    I don't understand what this article is saying. Why should a power outage mean that power supply to the hard drive gets cut off? I am using a laptop, and if the laptop battery is charged, surely that would keep the hard drive going when there's a power outage? I shall know if the battery is about to go out, and will shut down the laptop before that happens. In that case, what's the damage to the hard drive? The article appears to talk about only desktop computers.

    • sergei
      February 14, 2017 at 3:30 pm

      It also speaks of laptops with external hard drives attached, which people in many situations do, often on constant basis due to their line of work, etc.

    • Noah Dove
      April 28, 2019 at 11:14 am

      Unless its a power surge then every device is effected.

    • JB
      December 20, 2019 at 11:29 pm

      Figured that out all on your own, congradulations...

  5. beverley Fielden
    August 1, 2016 at 6:27 pm

    I'm suffering from a real enigma of a problem
    I'm in the uk and we don't have many surges or electrical storms
    However over the past three years I have had over 30 components fail on computers and in not exaggerating
    This is not just one machine
    It has happened on various computers I have bought
    Brand new desktops two of these
    Second hand spare laptops two of these
    And my most recent purchase a £1000 laptop
    It appears the the most failed components on the desk tops is the graphic card followed by the motherboards
    The laptop fail on the motherboards
    I have had other small devices stop working too like modems and powerline adaptors

    I am using a surge protectors
    I have all the earthing in my house checked and it is all fine and connected to an RCD

    I'm at my wits end on where or what to try next

    • seth
      August 11, 2016 at 4:47 am

      Hi beverley,

      This answer is no fun, but I moved into an old home a while back and had a similar issue of frequent unexplained computer failure. The answer ended up being that the entire house needed to be rewired. Your grounding may be good, but the wires could be old(or just bad for some reason). Maybe get that checked and good luck.

  6. Clinton
    April 26, 2015 at 7:27 am


    Please could someone help me to understand the effect of a brown-out on hardware, as this was not clearly addressed in the otherwise very useful and informative article. I have an iMac 27" (Late, 2013).

    I would like to use a solar powered battery device with a 150 Watt External modified sine wave inverter. According to the Mac website, my model will use approx. 78W when idle, and 180W at CPU Max.

    So, because I live in South Africa, where we now have load-shedding (planned black-outs depending on national energy grid pressure) I have invested in an EcoBoxx 160 DC + [Broken URL Removed].

    My question is thus: If I use my Mac with the device, and it happens to demand more than the 150W generated by the EcoBoxx, would this cause damage to any of its component parts?

    I will only be using MS Word on my Mac under these conditions, so I imagine that if I close all other applications then the power demand of the Mac should not approach CPU max?

    Also, if I ran it through a surge protector, would this make a difference?

    I would be extremely grateful for any advice or suggestions, as I am desperately trying to complete my PhD dissertation, and cannot afford to continuously suffer the effects of load-shedding!

    Thanks and Warmest Greetings,

    • Afitz
      April 28, 2015 at 4:05 am

      No damadge should occur, your computer will start to have artifactingnproblems, where white boxes appear randomly on screen, and your computer may crash because its not pulling enough power.

  7. Kamakshi
    April 14, 2015 at 7:55 pm

    Yes,I think this true

  8. ED
    September 23, 2014 at 8:06 pm

    Maybe I missed it or someone already posted a comment. You also have to unplug (or at least protect) your network connections such as a cable modem or DSL because electrical anomalies
    are just as likely to come in from them as the power during a lightning storm.
    Electrical anomalies can crash your system but they can also cause latent failures that may only show up months later or as intermittent failures which may not be associated with the spike or surge.

    • Joel L
      September 25, 2014 at 12:28 am

      Yes, absolutely. Most people who unplug their computers forget to unplug their modems/routers/ethernet cables. It's a terrible feeling when you think you've taken the proper precautions only to return to a lightning-zapped computer.

  9. Adrian
    September 15, 2014 at 12:18 am

    Honestly, I've never lost data due to a power outage...that doesn't mean that it'll never happen though.

    I have lost 2 tvs, a computer, a router and a modem to a freak electical storm though. Sad thing I wasn't home when it hit. I think it's good practice to unplug your expensive equipment when you're going to be away for a while.

    • Joel L
      September 16, 2014 at 5:27 pm

      Did all of those losses occur during the same storm? If so, that's crazy!

    • Kamakshi
      April 14, 2015 at 7:57 pm

      That's cool

  10. Jim Horn
    September 13, 2014 at 12:21 am

    Laptops take the external power and send some to the battery to recharge it and the rest to the computer circuitry. If the external power fails, the battery takes over. But "all the electricity is" NOT "being channeled through the battery" so anything that overstresses the input circuits will cause laptop failure. And repairs are almost always more expensive than replacement of the whole laptop (sigh).

    (from an electrical engineer who has the schematics for his and has rebuilt the internal supplies more than once)

    • Kamakshi
      April 14, 2015 at 7:56 pm


  11. Tajwar H
    September 12, 2014 at 7:30 pm

    I've moved away from Desktops permanently in the last few years. Since Laptops run on batteries anyway, should one be worried about Power Outages/Voltage Spikes (since all the electricity is being channelled through the battery to the circuitry)?

    • Kamakshi
      April 14, 2015 at 7:56 pm

      So what

  12. A41202813GMAIL
    September 12, 2014 at 4:34 pm

    For Turning Off, I Just 'Pull The Power Cord' 99% Of The Time.

    Sometimes The PC Refuses To Boot, So I Have To Load The BIOS Default Settings And Reset The Boot Order For All My Devices.

    Sometimes, Disks Need To Do Some Auto CHKDSK Before Normal Proceedings.

    No Big Deal - So Far.


    • Joel L
      September 16, 2014 at 5:26 pm

      You really shouldn't "pull the power cord" as it doesn't give your computer enough time to properly shut down system services, which is why you often run into boot issues. It could harm your disks as well. Always use the operating system's Shutdown procedure.

    • A41202813GMAIL
      September 16, 2014 at 11:08 pm

      Thank You For Responding.


    • Fart
      February 3, 2015 at 3:19 pm

      Worst advice every, do not follow this persons advice.

      Source: I am a software engineer, and have been dealing with computers for decades.

  13. dragonmouth
    September 11, 2014 at 10:34 pm

    All great advice ASSUMING one is by one's computer 24/7/365. Most of our power outages/power surges occur when when the weather is calm, very few during storms. a few occur during the night. I have two choices, either plug all my hardware into a generator or unplug everything when not in use. Neither choice is very useful.

  14. KT
    September 11, 2014 at 10:09 pm

    I actually had a software issue from a blackout. It was Windows XP about 8 years ago. I was on a "less than family friendly" website when the power went out. When it came back on, my pc had over 4,000 detected threats on it and the fake "fix your pc" windows took over! That's when I changed to Linux btw, I needed a more secure and free way to keep visiting those "less than family friendly" websites! GFCI receptacles are a good choice too for protecting your hardware.

  15. Amrit K
    September 11, 2014 at 6:21 pm

    If power fluctuation happens more often then it may fry your hardware... nice and crispy.
    Also it may cause fire hazards.