[John Rogers]

If you are running Windows 10 you can set an application to use only part of the "cores" in one of the new CPUs either Intel or AMD. Essentially you start the Task Manager, then select the tab for Details. Highlight the application name you want to control then Right Click and select Set Affinity. You will see the list of "Processors" starting at 0 and like in my case going to 7 since I have an AMD X8 CPU. Generally I would use this when converting video since HandBrake uses 100% of the CPUs available so I'll pick 3 or so for that application. That way I can do other things.
John