Windows 7: CPU behaving strange, running at 100%, unless Task manager is open

My computer has been behaving quite strange for a while.

My computer registers CPU usage at 100%. A desktop gadget that monitors my CPU says that all 4 cores are at 100%. However, the computer doesn't lag or anything. The only symptom of this is that the computer fan goes full blast as if to compensate for extra activity.

The strange part is that when I open the task manager, the CPU drops to normal. The gadget displays a normal usage, the fan slows down, and the Task manager shows the correct CPU usage. In fact, if the task manager is already on the performance tab when I open it, I can see the CPU usage bar start at 100% and immediately drop. If I close the task manager, the CPU shoots up to 100% again. It feels like the computer is trolling me or something.

Opening the resource monitor makes the CPU drop as well.

I scanned my computer with Microsoft Security Essentials and Malwarebyte's Anti-malware, and nothing came up.

The problem doesn't occur when the computer is in safe mode.



The computer has been doing this for several months. I just leave the task manager open and it's fine. The incorrect CPU usage doesn't have any adverse performance issues, but the fan on my computer is really loud, and I want to fix it because it bothers me that this is happening regardless.

Does this occur in safe mode or with a clean boot?

No, this does not occur in safe mode.

The virus scan didn't fix it either.

The CPU is normal when the resource monitor is open as well.

Since this isn't happening in safe mode, a driver or third party app might be causing the issue.

You can test the drivers during startup using driver verifier: Using Driver Verifier to identify issues with Drivers

Warning: follow all warnings suggested on this. and I have not used this myself.

Also found this as a possible culprit: Igfxupdate.exe forces cpu to load @ 100% - Microsoft Community

In addition establish a clean boot, use process explorer, system resources and these other Troubleshooting Steps for Windows 7

That was it! My problem is fixed now. Thanks!

Sweet. glad I could help

Code4240 do you remember anything that you might of installed/downloaded just before you got this problem?
Igfxupdate.exe

The reason I ask is because I helped a member about 2 weeks ago with the same problem. I'm just wondering if their is something in common that might help others.

Excellent suggestion Layback Bear, hopefully OP comes back with an answer....