M. Page @FrostyTech said:
With its Nidec F09A-12B1S2 fan rotating at default speed (est. 1500RPM via 3-pin fan power supply), the stock Intel Core 2 Duo heatsink produces a very quiet 36.7dBA noise. This fan model pulls 0.2A in operation, while the older stock Intel Pentium D fan draws 0.42A power. The latter spins faster but creates more noise as a result.