Burn-ins should be done after or during the OCing process, mainly to ensure system stability, and i'm sure there are more technical reasons i don't know. Either way, you should do a burn-in for a few hours once you have reached your desired OC. the main program used by most people here is called Prime95. its actually a Distributed Computing Application, but has a built in "Torture Test" function that is designed for and works very well for doing Burn-ins. just google Prime95 and download it. pretty simple, you will find the Torture Test function easily. good luck!