My heatsink fan is NOT spinning on my Athlon64. I just noticed this and I've been playing on the machine for a few days, even long sessions of intense 3D gaming. I know it used to spin when I first built it this past weekend. I have since set the Cool n' quiet option in BIOS to enabled though. Is this supposed to stop the fan from spinning when not needed? If not I hope I haven't burned up my CPU!