If you're using stock cooling, and your system has onboard cooling control, it sounds like your fan may have bad bearings that only make noise at elevated temps under load.
A friend installed a retail C2D with stock Intel cooling and found that, by removing the fan, cleaning the stock compound and replacing it with a very thin coating of Arctic Silver, his temps dropped significantly.
That won't address your noise problem, but it suggests that the factory installed cooling setup is far from ideal. Consider returning it for replacement or buying a better after market cooler.
Good luck.
