If you processor keeps running at or hits 100 percent for an extended period, you have a computer error because spikes like this are uncommon, according to PC World. The most likely cause of your constant processing is software-related.
Press "control, ALT and delete" at the same time to bring up task manager and view the CPU usage of your applications. Right-click on the offending application and the set the priority to low.
You also might have malicious software on your computer, such as a virus or trojan, causing excessive processor use. Run an anti-virus or anti-malware program and scan for malicious software.
Bugs in system files, such as drivers for your graphics card, may cause your processor to keep running. Tech Radar suggests running a search on known bugs that cause CPU spikes.