Windows system CPU usage continues to peek or stays at 100%

Determining what's utilizing the CPU

Each process that is running in Windows and the CPU usage it is using can be determined by opening the Windows Task Manager and clicking on the processes tab as shown in the image below.

Windows Task Manager Processes

Once this tab is open click the CPU button above the list of programs twice to organize the programs CPU usage from highest to lowest.

Note: If you do not see the processes tab your running an older version of Windows that does not have this feature.

As can be seen in the above example we have two processes running that are each taking up 50% of the CPU. The Image names FahCore_81.exe and System Idle Process. It is normal for a Windows computer to have a high System Idle Process.

However, in this case the other process "FahCore_81.exe" is using lots of the available CPU that may be concerning. In this situation we know that this Image Name is associated with Folding@Home a distributed systems project. However, if you are not familiar with what the process is, do a search to find additional information on the file.

If you need to regain CPU resources temporarily you can highlight processes utilizing high percentages and click the End Process button. However, often after rebooting the computer these processes will reappear.

Permanently keeping the TSR disabled

If you've End Tasked the program following the steps above to temporarily remove the program from starting up but it returns each time you start the computer you'll need to disable that program from starting each time Windows loads.

If you are unable to navigate in normal Windows or performing the above steps does not decrease your system resources back to a normal value try restarting Windows in Safe Mode.

Computer Trojan, Virus, Worm, Spyware or other malicious program

Computer Trojan's, Viruses, Worm's, Spyware, and other malicious programs designed to destroy or modify data on your computer or other computers attached to your computer or designed to attack other computers can utilize your system resources.

Make sure you have a spyware program installed on your computer and that it is up-to-date. If you do not have a spyware program installed on the computer it is highly recommended you install one now.

Additional information

  • See our CPU and Task Manager definitions for further information and related links on these terms.