If you have a multi-processor system, it is possible to select which CPU(s) an application uses.

Open Task Manager and select your application on the Processes tab. Right click the program name and choose Set Affinity. Uncheck the processors which should not run this application.

If you try to select a service, Set Affinity will be ignored.

NOTE: see tip 3542 ยป How can I permanently set the processor affinity for an application?