Remove all the Asus suite it is worthless and causes issues. You need to overclock in the bios. There isn't no telling how much voltage that crappy software is using to mildly overclock your cpu. Here is the app to uninstall it off your pc. Also cpus do tend to degrade after so long. Depending on how much voltage and heat output, it could have ill effects on it.
AI Suite Cleaner ToolThanks, Raja@ASUS
If you narrowed it down to BF3. Then it maybe just the game and the sound card helping the issue. Best thing is to try it on other games and see how it acts there. What drivers are you using on the Pheobus?
Official/Unofficial? Beta Tester For The Asus Pheobus ROG Xonar 2012 - 2013