Variable Speed Fan; Boxed Processor Fan Heatsink Set Points; Datasheet - Intel SL8J6 - Pentium 4 Processor Datasheet

7.3.2

Variable Speed Fan

The boxed processor fan operates 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 the 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
Table 32, can vary by a few degrees from fan heatsink to fan heatsink. The internal chassis
temperature should be kept below 38 ºC. Meeting the processor's temperature specification
(see Chapter
Note: 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
requirements).
Figure 22. Boxed Processor Fan Heatsink Set Points
Table 32. Boxed Processor Fan Heatsink Set Points
Boxed Processor Fan
Heatsink Set Point (ºC)
X ≤ 30 °C
Y = 34 °C
Z ≥ 38 °C
NOTES:
1. Set point variance is approximately ±1 °C from fan heatsink to fan heatsink.

Datasheet

5) is the responsibility of the system integrator.
Lower Set Point
Lowest Noise Level
X
Internal Chassis Temperature (Degrees C)
When the internal chassis temperature is below or equal to this set point,
the fan operates at its lowest speed. Recommended maximum internal
chassis temperature for nominal operating environment.
When the internal chassis temperature is at this point, the fan operates
between its lowest and highest speeds. Recommended maximum
internal chassis temperature for worst-case operating environment.
When the internal chassis temperature is above or equal to this set point,
the fan operates at its highest speed.
Boxed Processor Specifications
Increasing Fan
Speed & Noise
Y
Boxed Processor Fan Speed
§
Figure 22 and
Table 31 for the specific
Higher Set Point
Highest Noise Level
Z
Notes
1
1
81