written by: Trevor Parker•edited by: M.S. Smith•updated: 10/25/2010
Wondering why your CPU usage dips then spikes? What could be causing abnormal CPU usage? Find out symptoms of unusual CPU usage, possible causes, and fixes in this article.
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Understanding CPU Usage
Computers and laptops rely on a number of components to operate. One of the most important components in a computer is the CPU (central processing unit), or simply "processor." It is helpful to think of the CPU as the computer's brain, where mathematical operations, logical instructions, and input/output are processed.
It is no surprise, then, that CPU usage is related to how many programs are running on your computer, and the intensity of processing that those programs require. Video game software, three-dimensional modeling programs, audio processing, and video applications all use large amounts of processing time.
Even with great advances in processor technology, sometimes the CPU can be bogged down. The question is, do you know why? If your CPU usage dips then spikes, and you don't know why, it is a good idea to find out.
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A common cause of CPU usage fluctuation is antivirus software. Whenever antivirus software is scanning your computer, or examining running programs, it may take up a lot of CPU time. Antivirus software is usually much more beneficial than it is cumbersome. However, if you feel your antivirus software is not working efficiently, it is okay to shop around for other offerings. Be wary of imitation or fake antivirus software.
Sometimes the Explorer shell on Windows will hang, or use excessive CPU time. In such a case, it is suggested that you save any work and restart your computer. If it occurs frequently, it may be possible that your computer is infected with malware.
Another cause of excessive CPU usage is the web browser. Having too many browser windows or tabs open can sometimes bog down a computer. This is especially the case when the browser windows or tabs are opened to media-rich websites. Closing unneeded browser windows and tabs, or restarting the browser, usually fixes the problem.
Finally, viruses, malware, and spyware are notorious for bogging down the host computer. Running updated antivirus software, and running regular malware and spyware scans, is highly suggested.
As always, if you are using a processor-intensive application such as a video game, it is normal for the CPU to experience high usage.
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Investigating CPU Usage
To find out if a piece of software is hogging your CPU, simply open the task manager by right-clicking on the taskbar and selecting Start Task Manager. On Mac OS X, click the Applications icon on the Dock, then Utilities, Activity Monitor. In Task Manager, ensure that the Processes tab is selected, then sort the table by CPU usage by clicking on the CPU column header. On Mac OS X, click on the % CPU column header in Activity Monitor.
The image name (process name on Mac OS X) is displayed to the right. This identifies what process is consuming that percentage of the CPU time. Make note of the name of the process and then research to find out what program or application it is related to. Since the process may be critical to system function, it is not advised to forcibly end the process. Sometimes the process name will indicate what program it belongs to. Other times, it may be an unfamiliar or obscure process.