Hi Peter,

If your computer has an application that has a high memory or CPU usage. It will now require your operating system to be refreshed by performing a clean boot. This includes the resetting of system processes that are running on services.msc. To resolve your concern, visit this link and follow the instructions and go the section “How to perform a clean boot” for Windows.

In addition, you need at least 30% of free space on your hard drive for optimum results and updated BIOS (Basic Input/Output System) driver.

Let us know if the solution above works for you.

I performed a clean boot and it seems that ntoskrnl.exe does not cause any problems in this state, but when I change it back it is still there.

ntoskrnl.exe does scan your computer's cache and finds available driver updates on the Internet. Can you tell us if this background process is harming your computer? And how long does it take much memory and CPU usage every time you use your computer? Did you receive any error messages when it's running?

We're looking forward to your response.

It is completely random when it causes high CPU usage. It dosen't (as far as I can see) take up much memory, it just causes high CPU usage.

It spikes to about 20 - 90 % and stays like that for a second or so and causes my computer to freeze during that time. It can happen often, like every 5-10 minutes and sometimes it can go about 30 minutes. I do not recieve any error when this is happening.

At this time, we recommend performing a full system scan for your computer to see if there are unwanted programs and script that slowdown your computer's performance. To do this, follow the steps below to start scanning your computer by using Windows Defender:

1. Press Windows + S to open Search Box.
2. Type Windows Defender, then click it.
3. In Home tab, select Full under Scan options.
4. Click Scan now to begin the thorough scanning of your computer.
5. Wait for the process to finish.
6. If there are any findings, send us the results through screenshot.
7. Before closing the application, make sure that Windows Defender is always turned on.

In addition, you can set a schedule for Windows Defender to perform periodic scans for your PC. Visit this link for more information about how to set scan schedules.

Let us know if you need more assistance.

Hi,

ntoskrnl.exe is not the real culprit, something else is forcing the issue. If it stopped when you did a clean boot they something disabled was likely the root cause. So perform a Clean Boot again and if it stops enable only 1/2 the processes to see if it still remains clear. If so disable those and re-enable the other 1/2. When it shows up again diable 1/2 or that 1/2. Use that process of elimination until you find the cause. Keep in mind that such an issue could be the interaction of two or more of them.

If using an SSD or hybrid hard drive be sure it has the latest firmware.

Try the Clean Boot method to see if a startup program is involved - if so it is a
process of elimination :

Right Click the start button - Command Prompt (Admin) - at the prompt type in

MSCONFIG

and hit enter

How to perform a clean boot in Windows
https://support.microsoft.com/en-us/kb/929135

Other programs to help :

Autoruns - Free - See what programs are configured to startup automatically
when your system boots and you login. Autoruns also shows you the full list
of Registry and file locations where applications can configure auto-start settings.
http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx

Process Explorer - Free - Find out what files, registry keys and other objects
processes have open, which DLLs they have loaded, and more. This uniquely
powerful utility will even show you who owns each process.
http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

==================================================

More if needed - do all of these :

If you had a 3rd party antivirus on the OS you upgraded OR if you have one
now uninstall it and then run its maker's removal tool. Use Windows Defender
which in Windows 8/8.1/10 is a full antivirus. Despite all the hype out there
Windows Defender and the Windows Firewall are true superstars.

List of anti-malware program cleanup/uninstall tools
http://answers.microsoft.com/en-us/protect/wiki/mse-protect_start/list-of-anti-malware-product-removal-tools/2bcb53f7-7ab4-4ef9-ab3a-6aebfa322f75

Uninstallers (removal tools) for common antivirus software
http://kb.eset.com/esetkb/index?page=content&id=SOLN146 

===============================

Check this :

Right Click Start button - Control Panel - Troubleshooting - on right side click View all -
System Maintenance.

-----------------------------------------------------

Tips to improve PC performance in Windows 10 <-- read this link
https://support.microsoft.com/en-us/help/4002019/windows-10-improve-pc-performance

The below is additional help with some of the methods in the "Tips to improve...." link.
Windows Key + X - Command Prompt (Admin)

SFC /scannow

Note if that shows uncorrected errors - do the below regardless.

When that completes run these :

DISM /online /cleanup-image /scanhealth

DISM /online /cleanup-image /restorehealth

Note if that shows any uncorrected errors - do the below regardless.

Then restart the computer.

Be sure you are running the latest available BIOS and drivers.

Check with System Maker (Motherboard Maker for custom systems) for updates
to the BIOS, low level chipset drivers, and the major on-board and separate 
device drivers. Run DriverView - set VIEW to Hide Microsoft drivers - update
those without Dump in their name.

DriverView - Free - utility displays the list of all device drivers currently loaded
on your system. For each driver in the list, additional useful information is
displayed: load address of the driver, description, version, product name,
company that created the driver, and more.
http://www.nirsoft.net/utils/driverview.html

For Drivers check System Maker as fallbacks and Device Maker's which are the
most current. Control Panel - Device Manager - Display Adapter - write down
the make and complete model of your video adapter - double click - Driver's
tab - write down the version info. Now click UPdate Driver (this may not do
anything as MS is far behind certifying drivers) - then Right Click - Uninstall -
REBOOT this will refresh the driver stack.

Repeat that for Network - Network Card (NIC), Wifi, Sound, Mouse and Keyboard
if 3rd party with their own software and drivers and any other major device drivers
you have.

Now go to System Maker's site (Dell, HP, Toshiba as examples) (as rollback) and
then Device Maker's site (Realtek, Intel, Nvidia, ATI as examples) and get their
latest versions. (Look for BIOS, Chipset, and software updates at System Maker's
site while there.)

Download - SAVE - go to where you put them - Right Click - RUN AD ADMIN -
REBOOT after each installation.

Always check in Device Manager - Drivers tab to be sure the version you are
installing actually shows up. This is because some drivers rollback before the
latest is installed (sound drivers particularly do this) so install a driver - reboot
- check to be sure it is installed and repeat as needed.

Repeat at Device Makers - BTW at Device Makers DO NOT RUN THEIR SCANNER -
heck manually by model.

Manually look at manufacturer's sites for drivers - and Device Maker's sites.
http://pcsupport.about.com/od/driverssupport/ht/driverdlmfgr.htm

Hope this helps.
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Rob Brown - Microsoft MVP <- profile - Windows and Devices for IT : Bicycle - Mark Twain said it right.

Hello,

I had the exact same issue: ntoskrnl.exe was using 29-33% of the CPU constantly, every time I turned on the computer (I bought it not long ago, so I've had this issue for only a few weeks). Only the CPU usage was high, the memory usage was normal. 

A bit of history is needed: I bought a refurbished laptop from the UK, and started to use it with the pre-installed Win 10 Pro 64 bit, setting the default language to Hungarian upon first turning it on because it's my native language.

After reading this thread, I tried pretty much everything: clean boot disabling all the non-Microsoft services, disabling every single startup item, etc, nothing helped. Ntoskrnl was still eating about 30% of the CPU, right after starting the PC. 

Since I couldn't resolve the issue, I took screenshots of the task manager to post them here, but then I realized that I had set the language of Windows to Hungarian, which would make it difficult for others to understand them, so I set Windows back to English.

After the reboot, everything was back to normal: CPU usage went back to 0-1% when the PC was idle. I re-enabled all the startup programs and services I had disabled earlier, and it was still OK. I have used the laptop for a few days now, I've had no issues whatsoever since setting back the OS to English. 

Does anyone have any explanation of this phenomenon? 

Thanks in advance. I include the screenshots anyway (screenshots in Hungarian from the times when the problem persisted, final screenshot in English after setting back the default language). 

Kind regards,

Balint