Intel Pentium 4 Processor in the 478-PinPackage at 1.40 GHz, 1.50 GHz, 1.60 GHz, 1.70 GHz, 1.80 GHz, 1.90 GHz, and 2GHz

Boxed Processor Specifications
Datasheet 93
8.4.2 Variable Speed Fan
The boxed processor fan will operate at different speeds over a short range of internal
chassis temperatures. This allows the processor fan to operate at a lower speed and
noise level, while internal chassis temperatures are low. If internal chassis temperature
increases beyond a lower set point, the fan speed will rise linearly with the internal
temperature until the higher set point is reached. At that point, the fan speed is at its
maximum. As fan speed increases, so does fan noise levels. Systems should be designed
to provide adequate air around the boxed processor fan heatsink that remains below the
lower set point. These set points, represented in Figure 39 and Table 3 8,canvarybya
few degrees from fan heatsink to fan heatsink. The internal chassis temperature should be
kept below 40 ºC. Meeting the processor’s temperature specification (see Chapter 6.0)is
the responsibility of the system integrator.
Figure 38. Boxed Processor Fan Heatsink Airspace Keepout Requirements (side 2 view)
Figure 39. Boxed Processor Fan Heatsink Set Points