Troubleshooting : Need help with Ntoskrnl thread causing high CPU

 

Further research shows that many different hardware and/or driver problems can cause this problem.  Different solutions for the same symptoms are reported by many people in different forums, including BIOS and driver updates, bad hardware (motherboards, Ethernet adapters, etc.), and driver settings for a variety of hardware such as video, WiFi, and Ethernet adapters.  I'm sure you already know this, but I'll mention it for anyone researching this topic.

 

In my case, ACPI.sys+0x1af7c was causing a high interrupt, DPC, and context switch rate (~ 100,000/sec) and hence high CPU usage.  Searching for "ACPI.sys+0x1af7c" narrowed down the results so using this offset (or whatever offset others may have), as reported in Process Explorer, might be helpful to others.  I assume that this is the binary offset into ACPI.sys which locates where in the acpi.sys driver this is happening so may help narrow down the problem.

 

After trying many things, I found a forum entry with a suggestion to disable the Ethernet adapter's "Wake on Magic Packet" and "Wake on Pattern Match" in the driver's Advanced Tab in Device Manager.  This worked instantly for me without even having to reboot.  My adapter also has a "Wake on Magic Packet from power off state" option.  Either of the first two options mentioned above will cause the problem, but this last one can remain enabled without issue.  My adapter is an Intel I217-LM in a Dell E6540 laptop.

 

Here's the link to the original forum post:

 

 

I would upload a screen shot from my Ethernet adapter's settings menu but it exceeds the size allowed. 

 

So I'm a satisfied customer  and maybe this entry will help someone else.  Your suggestions pushed me in the right direction to find an answer.

 

Thanks for your help,

DoubleE