I recently found out that the power management inside the new I5 and I7 Intel processors is much more inteligent than what the older core2 has. For example a core2 would throttle back based on temperature only just before the critical point.
The newer I5s and I7s would turn cores on/off or independently, slow down depending on load, power consumption and temperature.
Basically this means that you might get less from your cpu if it runs hot – either because of the weather or because of inappropriate cooling,
Also overclockers should be careful. You might be happy that your machine is stable at the new speed but it could be that it’s only throttling down all the time.