The E6600 is an LGA775 Socket processor. As such, it probably suffers from Intel's very poorly designed heatsink/fan mounting arrangement. It is not easy to get right if you don't pay attention to the instructions and the latches are only good for a few install/uninstall operations before they fail.
If the heatsink is not held very tightly against the surface of the CPU, the CPU will tend to run very hot, causing the fan to run at insanely high speeds in an effort to compensate. You can find more info on this subject at http://www.supremelaw.org/systems/heatsinks/warning.htm
If you feel you require new latches, they can be found at http://industryeducation.com/Desktop_Heatsink-Kit_Fasteners_for_LGA775_fan_heatsinks__set_of_4_-P5904.aspx