Got 100% disk usage in Windows 10? So your computer is hanging and freezing. Same old Windows, right? Except you’re using a brand-new Windows 10 device; you’ve only had it a few days. So just what is going on?

Investigating, you discover that your system drive is running at 100%. Surely this can’t be, right? Sadly, it is. The latest versions of Windows have a problem with the drives being overworked, which slows down the operating system. This issue affects both hard disk drives (HDDs) and solid-state drives (SSDs).

Several fixes are available for this. But first, you need to trace the problem.

When the error was first discovered, only a few culprits were found. But as time passes, despite the 100% disk usage error being reported to Microsoft, more causes of this bug are discovered, not fewer.

Click the link above for each possible cause of the bug to see how to fix it.

Once you’ve established that there is a problem, you have several options available. Check the following steps one at a time, checking the disk usage in the Task Manager after each.

Note that even if you find a solution, a Windows Update could reset the changes you’ve made. Bookmarking this page will help you find it in the future and run through the fixes again.

1. Slow Performance? Run Disk Check

This performance issue is most obvious when attempting to use Windows Search to find a file or program, and anything else that requires the drive to do some work (perhaps copying and pasting a group of files).

To establish whether it is a problem that is affecting you, when your computer next slows down, use Task Manager to run a disk check.

First, press Ctrl+Alt+Del and select Task Manager (or right-click the Taskbar and select Task Manager, or hit Ctrl+Shift+Esc). Note that this may take some time to open with the drive being under strain.

why is 100 disk being used

On the Processes tab look for the Disk column. If you’re having problems with drive performance, this will be at 100%, and shaded red to indicate whether you have a problem or not.

Problem sectors on your HDD can cause the 100% disk usage issue in Windows 10. However, using Windows’ built-in disk check can fix this:

  1. Open Windows Explorer
  2. Select This PC
  3. Right-click on the C: drive and select Properties > Tools
  4. Under Error checking click on Check > Scan drive

Wait while the system scans the drive; a reboot may be required for a full disk repair. This should deal with the error.

2. Update Your Anti-Virus if Windows 10 Disk Is Running at 100%

As with any performance issue, the first thing to do is confirm that your computer hasn’t been infected with malware. Your security software should be able to deal with this, whether it’s a free app or a paid suite.

At the very least, tools like Malwarebytes Anti-Malware should be able to scan your system drive and detect any problems. Note that with a heavy load on your drive already this may take a while.

If threats are found, use the software’s recommendations to discard them and reboot. Next, check your drive’s performance again. Hopefully, you’ve resolved the issue; if not, then malware wasn’t to blame, so read on.

3. Disable Windows Search for Improved Disk Performance

The next thing to check is whether the 100% disk usage error has anything to do with Windows Search.

A bug in Windows 10 results in a “search loop” that causes an increased load on the system drive.

To stop this and prevent it from happening during your current session (until Windows is rebooted):

  1. Right-click Start
  2. Select Windows PowerShell (Admin)
  3. Enter net.exe stop “Windows search”

That should solve most issue. If there is no change, even after rebooting, you can permanently disable Windows Search and Indexing.

  1. Press WIN+R
  2. Type msc, then click OK
  3. In the Services window that opens find Windows Search and double-click to open
  4. In Windows Search Properties find Startup type and select Disabled
    how to reduce disk usage
  5. You can also click Stop to abort the service
  6. Click OK to save your changes.

A few moments after disabling Windows Search, your Windows 10 performance should improve considerably. If not, move on…

4. Disable SysMain to Fix 100% Disk Usage in Windows 10

Another Windows 10 feature identified as a potential cause of the 100% disk usage issue is the superfetch service. Since Windows 10 1809 (the 2018 Windows 10 October Update) this has been renamed to “SysMain.”

To prevent this service from causing the disk usage issue, open another Windows PowerShell (Admin) and enter:

net.exe stop sysmain
disk usage 100% in windows 10 fix

Again, wait a few moments to check whether this has had any effect on your computer’s performance. You should also run Check Disk in PowerShell:

chkdsk.exe /f /r

You’ll be informed that your PC must be rebooted for Check Disk to complete, so make sure you have closed all your applications first.

If this doesn’t work, it is likely that you’re experiencing a frustrating iteration of this issue that is simple to resolve.

5. Is Flash Causing the 100% Disk Usage Bug?

Flash remains one of the most vulnerable aspects of modern computing and should be disabled. Adobe killed off its multimedia plugin in 2020, so there’s little reason to keep using it, especially as Flash seems to be one of the most common culprits for the 100% hard disk usage in Windows 10 with the Google Chrome browser.

To disable Flash in Google Chrome browser:

  1. Open Menu > Settings > Privacy and security
  2. Click Site Settings
  3. Find Flash and set the toggle to Block sites from running Flash
  4. Click Back to confirm, then restart the browser

The next thing to do is update to the latest version of Chrome. In most cases this happens automatically, but if not just go to Menu > Help > About Google Chrome and wait for the update to complete.

If you can’t see any of the options, don’t worry. It simply means that your version of Chrome has already updated and no longer supports Flash.

6. Disk Usage at 100%? Switch Web Browsers

It may not be Flash that is impacting on your browser performance.

Another cause could be the browser itself, particularly if you’re using Google Chrome.

The obvious option is to choose a different browser. Windows 10 already has two browsers built in. You probably don’t want to use Internet Explorer, but Microsoft Edge is an adequate replacement for Chrome.

Several browsers are available, some better than others.

 

7. Is Skype Eating Disk Resources?

Another widely used application could also be causing your 100% HDD usage is Skype. In an era when online collaboration and video meetings is increasing, Skype is a likely culprit.

Since Skype has been more closely integrated with Windows 10, it is a little trickier to deal with. What you can do, however, is stop Skype from running to help determine if it is the cause of the issues.

  1. Press WIN+I to open Settings
  2. Go to Apps > Apps & features and scroll down to Skype
    Is Skype causing 100% of disk being used
  3. Click Skype, then Advanced options
  4. Here, scroll down to Terminate and click the button
    Terminate Skype to troubleshoot 100% disk use in Windows 10

Head back to the Task Manager to see the change. You may also consider finding a Skype alternative. If the 100% disk usage bug tends to happen straight after Windows loads, it’s a good idea to disable Skype from auto-loading. Under Runs at log-in, change the switch from On to Off.

Further issues with Skype can also be dealt with in this screen. You can RepairReset, and even Uninstall Skype to aid with your troubleshooting.

8. Resolve PCI-Express Firmware Bug

Some drivers don’t run quite as they should in Windows 10. One that has been discovered to be causing 100% HDD use is the StorAHCI.sys driver, which has a firmware bug. StorAHCI.sys intended for storage devices connected to the PC or laptop motherboard via Advanced Host Controller Interface PCI-Express.

To find out if this is the problem and rule it out:

  1. Right-click Start and choose Device Manager
  2. Expand IDE ATA/ATAPI Controllers
  3. Double-click the AHCI Controller entry
  4. In the Driver tab select Driver Details

If the driver listed as C:\Windows\system32\DRIVERS\storahci.sys, you could be affected by this bug. Next:

  1. Close the driver details box
  2. In the Details tab select Device instance path from the drop-down menu
  3. Right-click the value, then Copy.
  4. Launch Notepad and Paste the contents
  5. Next, press WIN+R and type regedit, and click OK
  6. Find HKEY_LOCAL_MACHINE\System\ CurrentControlSet\Enum\PCI\ and use the pasted string from Notepad to open the correct AHCI Controller, followed by the random number.

Here, expand Device Parameters\Interrupt Management\ MessageSignaledInterruptProperties and you should see MSISupported listed in the right-hand pane. Double-click this, then change the Value data: to 0.

Click OK to confirm and follow the instructions to restart Windows.

9. Is Steam Maxing Out Your HDD?

Enjoy gaming and have Steam installed? There’s a good chance this digital delivery system is causing 100% disk usage.

Usually this is due to update delivery, causing the background downloader to get caught in a loop. Clear the Steam cache to fix this.

First, make sure you have exited Steam. Where Steam is a likely cause of the 100% disk usage error, it may hang when you try to exit. In this case, use the Windows 10 Task Manager to close the software.

Next, open the WIN+R run box and enter

steam://flushconfig

You’ll see a dialogue box, informing you that content will be deleted.

Is the windows 10 disk 100 percent problem caused by Steam

Click OK to proceed.

Note that games and saves will be retained, so there is no risk of them being deleted.

10. Disable Diagnostic Tracking in Windows 10

Finally, it’s worth considering the impact of diagnostic tracking in Windows 10. A feature that you might have otherwise disabled for privacy reasons, it has been blamed for 100% HDD use on many PCs.

When it comes to reducing your hard disk drive usage, it’s quicker to simply disable the DiagTrack service. If this is the source of the 100% disk usage error in Windows 10, you can stop the service launching.

However, to do this you’ll need to access Command Prompt in administrator mode.

  1. Click Start and type cmd in the search box
  2. In the results select Run as administrator
  3. Input sc config “DiagTrack” start= disabled
  4. Input sc stop “DiagTrack”
why is disk space at 100% - it could be Windows diagnostic tracking

When you’re done, close the command prompt. You might also reboot Windows.

11. Windows Update Can Cause 100% Disk Usage

As well as affecting changes you make to your PC when fixing the 100% disk use problem, Windows Update can also be a cause.

This usually only happens when Windows Update has a problem (which is typically due to a file refusing to download). You have two options here:

  1. Leave your computer alone—shut all your open applications and wait. Eventually, the files will download, but depending on how Windows Update is scheduled on your computer, it may require a reboot.
  2. Shutdown your computer—once you’ve done that, restart and wait for Windows Update to resolve the problem.

Once the update has finished downloading, it’s wise to run it as soon as possible. Remember to check any previous fixes for 100% disk usage before proceeding; as noted above, Windows Update can reverse these fixes.

12. Reset Your Virtual Memory

Virtual memory is a combination of RAM and hard disk space and can be responsible for overuse of your HDD. If there isn’t enough RAM to perform a task, the HDD is used to supplement the RAM. Data moved to the HDD is then returned to RAM when required.

If you’ve made it this far and you’ve yet to solve the 100% disk usage issue, it could be worth resetting your virtual memory.

  1. Press Windows+Break/Pause
  2. On the right, find and click Advanced System Settings
    Open Windows Advanced System settings
  3. In the Advanced tab go to Performance > Settings
  4. Select the new Advanced tab
  5. Under the section labeled Virtual memory click Change
    Change virtual memory in Windows 10
  6. Clear the checkbox for Automatically manage paging file size for all drives
  7. Next, select the Windows drive (usually C:) and then Custom size
  8. Add an Initial size and a Maximum size; note both are measured in MB rather than GB
  9. Once the values are inputted, click Set then OK to continue
Can virtual memory cause the Windows 10 100% disk usage fault

These numbers can be confusing, so with the first value, rely on the recommended option. For the maximum value, aim for a figure no more than 1.5 times your system RAM.

For instance, a computer with 4GB of RAM should have no more than 6.5GB (6144MB).

The next step is to clear the temporary files that have been used in the previous virtual memory allocation.

  1. Open Run with WIN+R
  2. Enter temp and click OK
  3. In the temp directory, select all files with Ctrl+A and hit Delete

13. Activate High Performance Mode

Windows’ standard power modes are prone to the 100% disk usage bug but switching to high performance often overcomes the problem.

The downside, of course, is that your computer will use more power. Thanks to modern processor design this shouldn’t be a massive issue. However, notebooks and desktop replacement laptops may take a hit on battery life.

To change to high performance:

  1. Click WIN+X > Power Options
  2. In the Power & sleep screen click Additional power settings
  3. Here, choose High performance, then OK

If this isn’t a displayed option, you’ll need to create your own custom power plan. Click Create a power plan, then choose High performance. Give the plan a name, tweak any personal settings you need then select it as a power plan to use.

In a moment or two, the 100% disk usage issue should drop down to less than 10%.

14. Install the Latest SATA Drivers

Could a storage device driver be resulting in the 100% disk usage error?

Your Windows 10 computer almost certainly uses SATA connections for hard drives, SSDs, and optical drives. If the drivers aren’t up to date, the disk usage error can occur.

Avoid this by upgrading to the latest SATA drivers.

  1. Right click Start
  2. In the Power User menu select Device Manager
  3. Expand Storage controllers
  4. Identify the correct controller for your SATA devices
  5. To update, right-click on each controller and select Update driver
    disk usage 100% in Windows 10
  6. Select the Browse my computer for driver software option
  7. Next, choose then Let me pick from a list of available drivers on my computer
  8. Here, choose Standard AHCI Controller and see how this impacts performance

You may need to reboot Windows for this to take effect. Note that if it doesn’t work, you can still try this by checking the manufacturer’s website for a new driver. This can be installed using the instructions that accompany it.

15. Could Your PC’s Power Supply (PSU) Cause 100% Disk Usage?

There is a chance that your computer’s hardware is causing the 100% disk usage issue in Windows: specifically, the PSU.

If disk usage issues can be attributed to excessive disk activity, then it follows there might be a power-related cause.

100% disk usage has been spotted on Windows 10 laptops running on the battery. Once plugged into the power adaptor, the issue resolves. Similarly, the problem has been shown to alleviate once a new PSU is installed in a desktop PC.

Check our guide to new PC power supply units to help you choose a replacement.

16. Windows Help Is Causing 100% HDD Use

Another issue that has been traced to 100% disk usage in Windows 10 is the operating system’s built-in active help tool. You’ll have noticed this feature that pops up when you’re doing something for the first time with useful tips and suggestions.

If you suspect this is causing a problem in Windows 10 with disk usage, you can disable it:

  1. Press WIN+I to open Settings
  2. Here, select System > Notification & actions
  3. Find and disable Get tips, tricks and suggestions as you use Windows
    Windows tips and tricks suggestions can slow your PC

A few moments later, things should improve.

17. Is WaasMedicAgent.exe Slowing Down Windows 10?

Incorrectly identified as a virus or malware, WaasMedicAgent.exe (part of the Windows Update Medic Service) is a Microsoft system process that checks downloaded Windows Update files. If there is a problem with the data, the files are redownloaded – a process that could leave your HDD at 100%.

To fix this,

  1. Press WIN+R to open a Run box
  2. Enter regedit then OK to open Registry Editor
  3. Before proceeding, make a registry backup with File > Export, saving the backup somewhere safe
  4. In the browser bar, paste this path: Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WaaSMedicSvc
  5. In the right pane, right-click Start and choose Modify
  6. Set the Value data to 4 then OK to close

Disabling the update medic is an extreme step to take. However, it is one way to avoid Windows 10 disk usage hitting 100%.

Disk Usage Should Rarely Be 100%

Put simply, there is little reason for your disk load to be anything close to 100%, certainly not under normal usage. A slow computer is one with a problem, and if you cannot fix it by disabling a browser plugin, stopping services, or running your antivirus software, then the problem may well be hardware related.

Perhaps your drive is getting old; it may be defective, or the cables may need replacing.

Try these fixes the next time your Windows computer slows down. Be sure to check your Windows Experience Index periodically to identify performance issues in need of immediate resolution.