What.
I think you will find your OS is on your hard drive not your processer
ya
Don't listen to these clowns.
It's never a bad idea to reinstall the OS after a major upgrade like a new motherboard; thanks in part to things like our lovely friend, the registry. New MB, different brand of video card, different series of video card, etc. Those are things that could cause conflicts if you don't completely remove the old drivers when installing new ones.
Reinstalling the OS is a quick and easy fix to any driver conflict issues, unless you
want to hunt the registry for files that are causing problems that weren't removed by uninstalling or a registry cleaning program. It only takes maybe a half hour to back up your stuff and another half hour to install(Vista at least).
Bio Spark: The rest of your PC probably sucks too. You'll need a new PC to play most current video games, and you're PC will only get worse over time. I hoped you learned a lesson about impulsively buying games.