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How to identify the cause of 100% disk usage in Windows 10

The best way to identify why Windows 10 disk usage is at 100% is to consult the Windows Task Manager. The Windows Task Manager utility will show you exactly what’s causing your system to use 100% of your disk capacity — and then you’ll know which issue you need to fix.

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    Here’s how to identify the cause of 100% disk usage with Windows Task Manager:

    1. Right-click on the taskbar and select Task Manager.

      Opening Task Manager from the taskbar on Windows 10.
    2. On the main dashboard, click on the Disk column to see all running processes sorted by disk usage.

      Using the Task Manager to identify programs with high disk usage.
    3. Make sure the arrow in the Disk column is pointing down. That way, you’ll see the processes with the highest disk usage first.

    Look for items that appear orange and consume more than a few megabytes per second. Any process that takes more than 1 to 2 MB is a concern. Depending on the type of disk you’re using, even a small amount of excess disk usage can harm performance. 

    If your Task Manager reveals something obvious, find the cure below. If you see any of the following items causing high disk usage in Task Manager, click on the link to jump down directly to the solution:

    If Task Manager doesn't provide a clear answer, try these other solutions to reduce your disk usage:

    If your PC feels slow and if disk usage isn’t an issue, you might instead be suffering from high CPU usage or insufficient RAM.

    The 12 best ways to fix 100% disk usage in Windows 10

    With Task Manager identifying the processes causing high disk usage, the solution may be straightforward. Here, we’ve compiled the top 12 ways to fix Windows 10 100% disk usage — no matter what’s driving up your disk usage, you’ll be able to resolve the issue.

    1. Update Windows 10

    Microsoft frequently releases Windows 10 updates that fix bugs and plug security holes. These updates should be installed automatically, but if you’ve missed the latest release, updating Windows 10 can fix a variety of issues.

    To update Windows 10, open the Start menu and click Settings. From there, select Updates and Security and initiate the update. Once your PC finishes and restarts, the problem should be fixed.

    In some cases, you might see 100% disk usage because Windows is in the middle of updating. Windows replaces tens of thousands of files when updating, so everything else will slow down during the update process. In some cases, Windows may even become unresponsive.

    Windows updates usually download in the background and install automatically. If your disk usage spikes all of a sudden, Windows may have begun the update process. In such cases, when you navigate to Start > Settings > Updates and Security, you’ll see that the Windows update is in process:

    Windows Update popup showing a program update being downloaded and installed.Wait until Windows finishes the installation, and your disk usage should come back down. If you instead see “You’re up to date,” then you need to figure out what else could be causing Windows 10 to reach 100% disk usage.

    Windows Update popup showing you're up to date.If Windows 10 is up-to-date, look for another culprit of 100% disk usage

    2. Disable Superfetch

    Superfetch, or Service Host Superfetch, is a Windows feature introduced in Vista that analyzes your usage patterns, such as when you launch certain applications and how often. Superfetch then preloads data from those programs into your memory. In most cases, this works quite well, especially on older hard disks. But it’s not perfect.

    Some users complain that Superfetch causes constant hard disk usage. Gamers especially seem to hate Superfetch because it tends to preload the files of a game it thinks you want to play, while you’re actually playing a different game. Luckily, you don’t need Superfetch — and there are other ways to speed up your PC.

    If your hard disk is full, and if the following item shows up high on the list in Task Manager, you’re dealing with a Superfetch problem.

    Windows Superfetch causing high disk usage in Windows 10.Disable Superfetch to see if disk usage drops without any decrease in performance — it’s trial and error with this one. To disable Superfetch, press the Windows and R keys at the same time. Type in services.msc.

    Running Services in Windows 10.Hit OK. You’ll see a long list of services that Windows is running. Scroll down until you see SysMain.

    Viewing the Superfetch service in Windows 10.Under Startup type, click Disabled and hit OK. Reboot your system and see if performance improves. If not, turn Superfetch back on by completing the same steps — at the end, just select Automatic instead.

    3. Remove viruses and malware

    Is Task Manager showing you an unknown program with super-high disk usage? It might be a virus, spyware, or other malware. In addition to messing with your PC’s performance, malware can also steal your personal information, corrupt files or apps, and wreak other havoc. Follow our guide to get rid of viruses and malware immediately.

    To prevent malware infections, learn about the most dangerous current online threats and read our list of the best security and privacy tips.

    But there’s no substitute for having strong antivirus software. Since malware can play a huge role in pushing Windows 10 to 100% disk usage, stop whatever you’re doing now and install a free antivirus tool. AVG AntiVirus FREE not only provides real-time security updates, it also scans your machine to detect malware and performance issues.

    4. Reinstall or update your antivirus software

    High disk usage can also be caused by antivirus software — during a background scan, or if the tool malfunctions and gets stuck. Go into your antivirus tool’s dashboard to see if a scan is in process. If so, do not stop it. Your antivirus may be dealing with a nasty piece of malware.

    If the scan seems frozen, reboot your system and let it sit for a while until the antivirus stops. If it doesn’t stop, then you might need to reinstall the antivirus, update it, or find another one. AVG AntiVirus FREE is a resource-light solution you can try right now.

    5. Close background applications

    Running lots of applications at once may cause 100% disk usage in Windows 10. Uninstalling these programs often isn’t possible, because you may need them. Manually pausing the background apps is only a short-term solution, as many will restart upon bootup or run quietly in the background.

    The patented Sleep Mode in AVG TuneUp identifies resource-intensive background applications and deactivates them to free you from 100% disk usage. When you need to use an app, AVG will reactivate it immediately. Plus, AVG TuneUp will identify unnecessary apps and remove that bloatware.

    Using Sleep Mode in AVG TuneUp to help fix 100% disk usage in Windows 10.AVG TuneUp will snooze background apps and startup processes to reduce disk usage.

    Try Sleep Mode out for yourself. Download and install AVG TuneUp, then go to Speed Up and click on Background & startup programs. You can also remove junk files and bloatware, optimize your hard disk, and easily perform other PC maintenance with AVG TuneUp.

    6. Reset or reinstall synchronization tools

    Tools like OneDrive or Dropbox take time to synchronize all files. But they can sometimes get stuck and push disk usage to 100% if they’re still trying to synchronize after the process is done. That happens often with large amounts of data.

    To fix this, you can reset the programs or reinstall them. For example, you can reset OneDrive by pressing the Windows and R keys at the same time and entering the following command: 

    %localappdata%\Microsoft\OneDrive\onedrive.exe /reset 

    After clicking OK, OneDrive will reset and resync your files. This often solves issues with constant disk usage. So check to see if it’s your sync tool clogging up your disk, and try a repair install to fix it.

    7. Rebuild the Windows Search index

    The index in Windows Search helps you find files, folders, emails, and even the content of some of those files instantly. To do that, it scans your hard disk and turns it into a super-fast index to give you immediate results.

    Unfortunately, the search feature can lose control as it keeps on indexing, with no end in sight — all the way up to 100% disk usage.

    In such cases, it’s best to rebuild the index. Click on the Start button and type indexing.

    Launching indexing options to rebuild the Search Index in Windows 10.

    Click on Indexing Options. From there, select Advanced and hit the Rebuild button. That will completely erase the index, rebuild it, and hopefully fix any errors that were causing 100% disk usage in Windows 10.

    8. Repair hard disk issues

    A structural or physical defect can also be responsible for 100% disk usage in Windows 10. To check your disk for errors, try AVG’s Disk Doctor, another custom built-in feature in AVG TuneUp.

    To launch Disk Doctor, open AVG TuneUp and click on the All functions option in the Action Center. Fire up Disk Doctor and run a check.

    The Disk Doctor tool in AVG TuneUp

    If AVG TuneUp finds an error, it will fix it automatically. But if Disk Doctor doesn’t work, or if it keeps attempting to fix an issue, you might be looking at a defective hard disk. To prevent data loss, get your files off that disk as quickly as possible. Either copy them to an external hard disk or clone your hard drive and then replace the drive with a new one.

    9. Delete malfunctioning page files

    Whenever your PC runs out of free memory (RAM), it uses a “page file” on your hard disk to expand its memory. Let’s say you’re editing a 10 GB video file, but you have only 8 GB of memory (at least 2 to 3 GB of which are taken up by Windows and your apps). Your PC will use the page file on your disk as expanded memory. 

    Over time, this page file can become defective and cause unexpected slowdowns and high disk usage. To fix it, delete that page file and create a new one — press the Windows and R keys at the same time and type sysdm.cpl.

    Opening System Properties to manage paging file size.

    Click OK and go to Advanced > Performance > Settings > Advanced > Change. Uncheck Automatically manage paging file size for all drives and then select No paging file. Hit Set and reboot your system.

    Repeat all those steps again, select System managed size, and hit Set. Then, check Automatically manage paging file size for all drives.

    Changing virtual memory and page file in Windows 10.Not sure if your PC is using page files? Try checking how much RAM you have and then looking at the size of large files you typically work with to figure it out.

    10. Delete temporary files

    Deleting temporary files helps free up space and prevent issues. And in rare cases, bugs with temporary files can cause a Windows process or application to create hundreds or thousands of files and propel your disk usage up to 100%.

    A bug with temporary files in Windows 10.Delete the temporary files to fix the issue. And to regularly clean up temporary files without lifting a finger, download AVG TuneUp and give its disk cleaning functionality a spin. It’ll scan your machine for junk files and bloatware, letting you safely delete them and optimize your computer for the best possible performance.

    11. Update drivers

    Drivers control all the hardware in your computer, including your hard disk controller and the hard drive itself. A bug in an outdated driver could push Windows 10 to 100% disk usage. See our guides to update your graphics drivers and make sure you have the latest audio drivers.

    Make things easier with AVG Driver Updater, which can scan 8 million drivers so you don’t have to hunt around and update each one. Its easy-to-use interface will find and update your outdated or broken drivers, fix your problems, and return your computer to optimal performance. Download it today and try a free scan.

    Driver Updater in AVG TuneUP scanning for outdated drivers.

    12. Update hard drive firmware

    The software inside your hard drive is known as firmware. Recent firmware releases can help fix performance issues or unnecessary read/write operations. You can check if there’s an update available. 

    First, figure out which hard drive you have (if you don’t already know). Right-click on the Start button and select Device Manager. Expand the Disk drives section and look at the exact names of your drives:

    Find the exact names of your disk drives.

    In this example, the main drive is the Samsung SSD 970 EVO Plus. So you’d visit Samsung’s support pages to see if there’s an update available — and voila! There’s new firmware available.

    Updating firmware through Samsung's support pages.

    Download the firmware, then restart your computer to see if it fixes your problem with high disk usage.

    What causes high disk usage?

    If you’re at 100% disk usage in Windows 10, the issue could result from Windows itself or a variety of other programs. From Windows Superfetch, to a virus or malware, to outdated drivers or firmware, there are many causes. Often, your problem will be the result of several issues.

    See above for our detailed explanations of Windows 10 100% disk usage causes and fixes.

    How do you know high disk usage is slowing down your PC?

    You’ll know that high disk usage is slowing down your PC because your PC will feel slower when you aren’t using it for anything resource-intensive. For example, if you’re browsing the web or opening a photo stored on your hard disk, but those tasks take five to ten seconds instead of just one, then high disk usage is likely the culprit. 

    Here are a few examples of when you can assume your hard disk is being used more than usual:

    • Opening a folder of photos and videos: The preview thumbnails take a long time to load, and the green bar at the top of Windows Explorer fills up very slowly.  

    • Gaming: Even if you have a powerful gaming PC, loading a game or a new level takes noticeably longer, and there are occasional stutters. For example, the game randomly stops for one or two seconds as it’s loading new data into its memory, and the hard disk can’t keep up. 

    • Streaming: Your audio or video player is constantly buffering or displaying blurry or interrupted playback that disrupts your online stream.

    • Audible noises: Old-school mechanical hard disks are still quite noisy and make rattling noises when busy. If that happens, there’s disk thrashing going on. 

    • General lagginess: Weird lags when clicking on items, or opening menus or applications.

    The clearest way to find out that high disk usage is slowing down your PC is to consult Task Manager. Any process that consumes more than a few MB per second for a prolonged period of time is worth looking into, regardless of the performance impact.

    For example, on a seven-year-old HP laptop with an old mechanical drive, the maximum read and write speeds are about 40 to 50 MB per second. If a single process takes up 25 to 30 MB, you might see 100% disk usage sooner than you expect.

    But even a gaming PC with a super-fast NVME M2 SSD — with transfer speeds of up to 5 GB per second — can fall victim to 100% disk usage.

    As seen in Task Manager, gaming PCs can have transfer speeds of up 7 GB per second.A computer running Windows 10 at 100% disk usage is an inefficient computer — and that’s where AVG TuneUp can help. By cleaning out unneeded data, removing unwanted programs, and optimizing your PC with our patented, built-in Sleep Mode, AVG TuneUp reduces the strain on your hard disk and keeps your PC running like new.

    Can running Windows 10 at 100% disk usage damage my disk?

    If your Windows 10 disk usage is at 100% for a long period of time, you might see permanent damage. Constant disk usage increases the temperature and thus the chance that your disk will fail.

    There’s nothing wrong with 100% disk usage for a few minutes or even an hour. But if your disk is constantly at maximum capacity, and if this persists for several days at a time, performance may unravel.

    High disk usage is a problem with an HDD or SSD. Mechanical disks have a physical head that moves across the disk to read and write to it. Sustained 100% usage can lead to mechanical failure. On a modern SSD, the lifespan of the individual cells can decrease if you’re constantly writing and deleting data.

    It’s unlikely that you’ll experience data or hardware loss in the short term, but it’s definitely a possibility if high disk usage persists. You should identify the culprit and learn how to fix 100% disk usage as soon as possible.

    Low memory and high usage

    As discussed above, once your PC runs out of RAM, it uses a virtual page file on your disk. If you don’t have enough RAM to support the programs you use, you’ll force your PC to constantly dip into this page file. That happens especially with 4 GB of RAM or less. In that case, you should update your RAM.

    See our detailed guide to find out how powerful a computer you really need.

    How not to fix Windows 10 at 100% disk usage

    There are a lot of tips and tricks out there to fix high disk usage. Some are useful, while others are unhelpful or dangerous.

    • Don’t disable your antivirus: Turning off your AV will put you at risk. If your antivirus is causing high disk usage, check out our antivirus advice above. 

    • Don’t disable disk defragmentation or turn it off: If a defragmentation process is going on, Windows will pause it while you’re working. Let it do its thing while you’re not working, and do not turn it off.

    • Don’t disable Windows Update: Windows Update is critical to maintaining your security and fixing bugs. While your PC may slow down temporarily while updating, you should always keep your PC updated.

    Optimize your hard disk with AVG TuneUp

    Hopefully this article has helped you solve all the potential causes of 100% disk usage. To prevent it from happening again, uninstall programs you don’t need, clean up files, and make sure background processes don’t bog you down.

    AVG TuneUp will automatically take care of all of that. It’s an all-in-one tool dedicated to restoring your PC to prime performance — and making 100% disk usage a thing of the past. Try it free today.

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