Already discussed here:
http://www.fsdreamteam.com/forum/index.php?topic=6825.0As explained in the other thread, overclocking doesn't always result in deactivation, it does only on some systems (if it wasn't like this, we would have the forum flooded by reports, considering how common overclocking is) but, it will not cause the activation to be CONSUMED. The system recognize the PC is the same so, even if it's asking for a reactivation, it will not consider it a major change, and not use one of your activations.