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If your computer is suffering from high CPU usage How to Fix High CPU Usage in Windows How to Fix High CPU Usage in Windows If your computer fans frequently hit top speeds, it's a sign that your CPU is fully loaded. Simultaneously, your computer may slow down. That's annoying, especially if you're not actually doing anything. Read More and the culprit process is called “system interrupts”, then you are dealing with a hardware or driver issue.

In this post, we explain what system interrupts are and how you can find and fix the underlying cause of their high CPU usage.

What Is “System Interrupts”?

System interrupts appears as a Windows process in your Task Manager, but it’s not really a process. Rather, it’s a kind of representative that reports the CPU usage of all interrupts that happen on a lower system level.

Windows Interrupts Task Manager

Interrupts can originate from software or hardware, including the processor itself. Wikipedia explains:

An interrupt alerts the processor to a high-priority condition requiring the interruption of the current code the processor is executing. The processor responds by suspending its current activities, saving its state, and executing a function called an interrupt handler to deal with the event.

When the interrupt handler task is completed, the processor resumes the state at which it was interrupted.

Interrupts are a form of communication between software and hardware with the CPU. For example, when you type on your keyboard, the respective hardware and software sends interrupts to the CPU to inform it about the task at hand and to trigger the necessary processing.

Try moving your mouse and watch what happens to the CPU usage of system interrupts to understand what that means.

Interrupts can signal to the CPU that an error occurred and this can cause the CPU usage of system interrupts to increase. On a healthy system, system interrupts will hover between 0.1% and 2% of CPU usage, depending on the CPU frequency, running software, and attached hardware.

Even peaks of 3% to 7% can be considered within the normal range, depending on your system setup.

How to Fix the High CPU Usage

If system interrupts constantly hogs more than 5% to 10% of your CPU, something is wrong and you’re most likely dealing with a hardware issue. We’ll help you get to the bottom of this.

The first fix you should always try is to reboot your computer Why Does Rebooting Your Computer Fix So Many Issues? Why Does Rebooting Your Computer Fix So Many Issues? "Have you tried rebooting?" It's technical advice that gets thrown around a lot, but there's a reason: it works. Not just for PCs, but a wide range of devices. We explain why. Read More .

1. Check Hardware Drivers

To quickly check whether you’re dealing with a driver issue, you can run the DPC Latency Checker. Deferred Procedure Call (DPC) is a process related to system interrupts. When the interrupt handler needs to defer a lower priority task until later, it calls on the DPC.

DPC Latency Checker was designed to analyze whether your system can properly handle real-time audio or video streaming by checking the latency of kernel-mode device drivers. It’s is a quick way to reveal issues and the tool requires no installation.

If you see red bars, i.e. drop-outs due to high latency, something is off.

DPC Latency Checker

You can either try to find the culprit or — if the problem first occurred recently — roll back recent driver updates (Windows 10) Take Back Control Over Driver Updates in Windows 10 Take Back Control Over Driver Updates in Windows 10 A bad Windows driver can ruin your day. In Windows 10, Windows Update automatically updates hardware drivers. If you suffer the consequences, let us show you how to roll back your driver and block future... Read More or update your drivers How to Find & Replace Outdated Windows Drivers How to Find & Replace Outdated Windows Drivers Your drivers might be outdated and need updating, but how are you to know? First, don't fix it if it ain't broke! If drivers do need updating, though, here are your options. Read More with standard versions. Drivers that caused issues in the past How to Find & Fix AMD or ATI Display Drivers in Windows How to Find & Fix AMD or ATI Display Drivers in Windows After being acquired by AMD, the ATI brand name hasn't been around for years, but old graphics cards are still around. If you're still using one, here are some maintenance tips. Read More were AMD SATA, HD audio device, and missing Bluetooth drivers.

Alternatively, you can install and run LatencyMon, a latency monitor, to find the driver files with the highest DPC count. Press the Start / Play button, then switch to the Drivers tab, and sort the driver files by DPC count.

LatencyMon

Drivers with a high DPC count potentially cause a high number of interruptions.

2. Disable Internal Devices

Rather than randomly updating drivers, or if you have found potential offenders, you can disable individual device drivers to identify the culprit.

Go to the Start Menu, search for and open the Device Manager (also found in the Control Panel), expand the peripherals listed below, right-click a device and select Disable.

Do this for one device at a time, check the CPU usage of system interrupts or re-run DPC Latency Checker, then right-click the device and select Enable before moving on to the next device.

These devices are the most likely culprits:

  • Network adapters
  • Internal modems
  • Internal sound devices
  • Any add-on cards, like a TV tuner card, ISDN or DSL adapers, or modems

If none of these are to blame, you can proceed with disabling (and re-enabling) other non-essential drivers.

Never disable any drivers necessary to run your system, including anything listed under Computer, Processors, and System device.

Also don’t try to disable the display adapters, the disk drive that runs your system, IDE controllers, your keyboard or mouse (unless you have an alternative input device, such as a touch pad), or your monitor.

3. Unplug or Disable External Devices

DPC Latency Checker didn’t find anything? Maybe the problem is caused by USB hardware. You can either unplug it or — while you’re in the Device Manager (see above) — disable USB Root Hubs, i.e. blocking external hardware from interrupting the CPU.

In the Device Manager, find the entry Universal Serial Bus controllers and disable any USB Root Hub entry you can find.

Disable USB Root Hub

If you’re using an external keyboard or a USB (Bluetooth) mouse, they might stop functioning. Be sure to have an alternative method of re-enabling the device!

4. Exclude Failing Hardware

If a corrupt driver can cause system interrupts, so can failing hardware. In that case, updating your drivers won’t solve the issue. But if disabling the entire device fixed it, you should follow our guide to test your PC for failing hardware How To Test Your PC For Failing Hardware How To Test Your PC For Failing Hardware Good PC ownership is a lot like good car ownership. You do more than just use it, you learn something about how it works. You don't need to be a PC technician or a mechanic,... Read More .

perfmon-resource-overview

Note: System interrupts could also be caused by a faulty power supply Every Computer Dies In The End: Learn What Parts Can Fail, & What To Do About It Every Computer Dies In The End: Learn What Parts Can Fail, & What To Do About It Most computers develop problems over time. Learning what they are and how you can deal with them is important if you don't want to be paying through the teeth for professional repairs. Don't worry though... Read More or laptop charger. Try to replace or unplug that, too.

5. Disable Sound Effects

If you’re on Windows 7, this may be the solution you’re looking for.

Right-click the speaker icon in your system tray, select Playback devices, double-click your Default Device (speaker) to open Properties, head to the Enhancements tab, and Disable all sound effects. Confirm with OK and check how system interrupts is doing now.

6. Update Your BIOS

The BIOS Discover Your BIOS & Learn How to Make the Most of It Discover Your BIOS & Learn How to Make the Most of It What the heck is the BIOS, anyway? Is it really that important to know? We think so and fortunately it's pretty easy. Let us introduce you. Read More is the first piece of software that is executed when you turn on your computer. It helps your operating system to boot. First, identify your BIOS version and check the manufacturer’s website for updates and installation instructions.

To find out your BIOS version, press Windows key + R, type cmd, hit Enter, and execute the following two commands, one after the other:

1. systeminfo | findstr /I /c:bios
2. wmic bios get manufacturer, smbiosbiosversion

Note that the I in /I is a capital i, not a lower case L.

BIOS Version

Note: Updating the BIOS shouldn’t be taken lightly. Make sure to back up your system How to Create an ISO Image of Your Windows System How to Create an ISO Image of Your Windows System Need a quick and easy way to backup and restore Windows without relying on backup tools or the cloud? It's time to learn how to make an ISO image of your Windows PC. Read More  first.

System Interrupts Can Be Tricky

System interrupts can have many different causes. Did you reboot your computer as instructed above? We hope you were able to fix the issue.

What brought the relief in your case and how did you track down the issue? Please share your solution with fellow sufferers in the comments.

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  1. Josh
    June 26, 2017 at 9:01 pm

    For me it was the audio configuration. In my case, I had to enable at least one of the microphone devices as well as one of the playback devices. It had to be an available device (not marked as unplugged) and it had to be marked as the default device. After each change you make, enabling devices and setting them as the default, you may notice the CPU usage for the interrupt process drop. However, you should wait ten to twenty seconds to make sure it stays that way. If it doesn't then enable another (plugged in/available device) device. Just use the "process of elimination" to find the culprit audio device. If you want to quickly test if audio is your issue like mine, just enable every device to see if the interrupt process drops to a reasonable level. (mine dropped to roughly 1%) Remember to wait around 20 seconds to make sure the process stays this way. If it isn't an audio device maybe check other device types that can be enabled/disabled and go the same process as the audio instructions. My guess is the interrupt was being sent to my device/s, because the device was disabled and needed to stay disabled. So, the processor was instructed to do this with interrupt signals. Hope this helps someone!

    -josh

    • Tina Sieber
      June 26, 2017 at 10:36 pm

      Thank you for sharing your culprit and fix, Josh! How in the world did you figure this out? I'd never guessed that a disabled device could cause system interrupts.

      • Josh
        June 27, 2017 at 12:09 am

        Actually, just got back on to clarify with you that wasn't a permanent fix. I couldn't leave it like this! I'm too nice. I noticed it getting worse again after I closed the sound config dialog. (this very well will happen to you also. If so, here you go! You might want to do this anyway, however, just in case. unless you don't want to "rock the boat" until it rocks itself...) After this, I narrowed it down to the recording device tab in the audio dialog. Every time I opened the tab for recording the interrupt issue would stop. So I figured, hey I'll disable all my sound devices in device manager. After doing this, the interrupt was still running at 20%. So I went deeper. I opened up the sound controller by expanding System Devices in the device manager, checked the "High Definition Audio Controller". (there were two listed, because I had multiple audio sources, with different manufacturers, and several different audio devices from each of these. This included playback and recording devices.) I disabled both (Not sure if it's necessary, but I uninstalled one of them if you want to take the EXACT same path as me; I would suggest disabling both first) After disabling the second audio controller it asks for a reboot. Go ahead and reboot, and when it starts up again re-enable the two audio controllers, since you will have no audio devices in the sound manager. After this, all is well. Interrupt process, at least so far, is normal and the audio devices can be "played with" however you please!! New theory though, although my original post is a good diagnosis tool for the issue, the real problem seems to be conflicting audio controllers. For some reason they seem to "shape up" after they're disabled, and work perfect in every aspect when you re-enable both after the restart. Maybe one didn't get configured properly when the other sound driver and controller was installed and created. Either way, seems to be a bug in multiple audio drivers/devices which use different audio controllers. Regardless of theory, it was a long track down for sure, but there you go!!
        To answer your other question. I just tracked down things I new an interrupt would interact with constantly if it had to continue to "interrupt" the hardware. That came down to network adapters and audio devices. Only those two, I suppose, since I got it after checking the audio devices. Otherwise, I would have hit up display, plugged in usb devices, blah, blah... After that, I just honed in on audio devices and worked up from the application level, to the device driver level, and eventually, in this post, the system level. Process of elimination. From easy to mess with, to the hardest to mess with. And a loooooooot of watching the "Process Hacker" task manager application. How fun! : |

        -Josh

        • Tina Sieber
          June 27, 2017 at 12:19 am

          Oh wow, that's dedication. What's your day job? If it isn't in IT, engineering, or customer support, you may be in the wrong profession. ;) Thank you for being so diligent and following up!

        • Josh
          June 27, 2017 at 1:09 pm

          Also, one last go at it may be to try each controller (within the device manager, under system category. See previous post) and see if disabling it and leaving the other enabled to see if that keeps the interrupt working properly. That should work if there are still issues for some reason after trying everything else. Just make sure the controller you disable is not the audio device you want to continue to use. If it only works when you disable a specific controller and leave the other one enabled to correct it, then the disabled controller is likely the device or driver/s you should look into. (maybe a reinstall, etc.) Otherwise, the issue was just having more than one audio controller active. Like I said, however, this could apply to different devices than an audio controller so if multiple audio controllers don't apply to you, look into other devices for the same issue.

      • Josh
        June 27, 2017 at 12:14 am

        Oh, last thing, disabled devices really aren't disabled. It's the software for the audio device dialog that stops it at the application level. The application doesn't even go as far as disabling it by the driver standards in the device manager. By this logic I started to enable devices to see if the interrupt process was affected and it was. just went from there.

      • Josh
        June 27, 2017 at 12:25 am

        Nah, I'm in the right profession haha. I'm a programmer and networker. At least that was my dual major. My actual job is as a programmer. Plus I like the low level stuff. Actually helps with the programming when you get a really weird bug in one of your applications for example. (like microsoft developers do in this case, lol) It's all about lots, and lots of information!

  2. amir
    April 9, 2017 at 4:17 pm

    thank you for all this useful post.
    my CPU usage stays steadily at 20% while the system is idle in windows 10.(mostly caused by processes system and system interrupts)
    after changing the DVD drive with systems HDD and placing an SSD in the HDD bay. my system has been experiencing the mentioned problem in which CPU usage doesn't go below 20%.
    my system config:
    Asus laptop k550jx
    corei7-4720HQ
    12 GB ram
    950M graphics
    1 TB HDD (in place of DVD drive bay)
    120 GB SDD (in place of HDD bay)

    • Dominator
      July 9, 2017 at 2:55 pm

      Hi,
      Just found a solution for this, I had the exact same problem. Your HDD caddy should have a switch around the connector (inside or outside, depends on the model). Push it and it should be fine.

      • amir
        July 9, 2017 at 4:49 pm

        Tnx. It really helped me and this was the only solution that worked

      • Tina Sieber
        July 16, 2017 at 2:44 am

        Thank you for sharing your solution, Dominator!

  3. Timothy Poplaski
    December 25, 2016 at 2:27 am

    The most common hardware cause of interrupt issues I've come across are caused by IDE controller settings on older systems. They can spike to 99% or more making a system reeeeeaaallllyyy slllllowwww. (Which of course is why I was asked to take a look.)

    Somehow the setting gets switched from DMA to PIO. Switching it back to DMA usually fixes the problem.

    A lot of older systems that are still plenty fast for Windows 10 have IDE controllers. The one that I'm using to write this comment for example. :)

    • Tina Sieber
      December 25, 2016 at 8:58 pm

      Thank you for the tip, Timothy! That's something I would not have thought of. How did you discover this bug?

    • Jorge Ponce
      August 22, 2017 at 5:16 pm

      Thank you so much Timothy for the hint!!!!.

      My problem was an interrupts process consuming cpu about 90% percent (also 100%) in an old laptop running Windows XP, 1gb of Ram and 1,70Ghz procesor Intel Pentium M.

      The solution start from this hint, I also searched in a lot of pages and finally change (with a .vbs script that i found in a web related to this topic) the primary IDE channel PIO to DMA (Device Administrator of my PC), reducing interrupts from 99-100% to 0,01-9% (considering old laptop).

  4. James Boelter
    June 5, 2016 at 2:07 pm

    Outstanding article. Helped me understand what's going on inside the PC a lot better than before.

    • Tina Sieber
      June 5, 2016 at 8:07 pm

      Glad to hear you found this article helpful!

  5. Anonymous
    May 19, 2016 at 1:56 pm

    Tina, DPC Latency Tracker mentions on their site that readings for Windows 8 (and presumably all newer versions) are incorrect. They do also say that they're working on an updated version, and that it'll be available on their site as soon as it's available.

    • Tina Sieber
      May 19, 2016 at 4:21 pm

      Thanks for the heads-up, Kelsey! I saw that message on Windows 8 compatibility, but didn't notice any unusual readings on my Windows 10 device (no suspicious system interrupts, either). Maybe it works well enough to be a good indicator.