Variable Speed Fan; Boxed Processor Fan Heatsink Set Points - Intel 2ND GENERATION CORE PROCESSOR FAMILY DESKTOP - THERMAL MECHANICAL SPECIFICATIONS AND DESIGN GUIDELINES 01-2011 Specifications

11.4.2

Variable Speed Fan

If the boxed processor fan heatsink 4-pin connector is connected to a 3-pin
motherboard header it will operate as follows:
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
cooler then lower set point. These set points, represented in
Table 11-2, can vary by a 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
The motherboard must supply a constant +12 V to the processor's power header to
ensure proper operation of the variable speed fan for the boxed processor. Refer to
Table 11-1
Figure 11-9. Boxed Processor Fan Heatsink Set Points
100
Chapter 6) is the responsibility of the system integrator.
for the specific requirements.
Boxed Processor Specifications
Figure 11-9
Thermal/Mechanical Specifications and Design Guidelines
and