Intel 2 Quad Q8400S AT80580AJ0674ML User Manual

100

Datasheet

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 

and 

, 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 

) is the responsibility of the system 

integrator.

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 

 for the specific requirements.

X ≤ 30

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.

1

1. Set point variance is approximately ±1 °C from fan heatsink to fan heatsink.

Y = 35

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.

-

Z ≥ 39

When the internal chassis temperature is above or equal to this 
set point, the fan operates at its highest speed.

-

Lower Set Point

Lowest Noise Level

Internal Chassis Temperature (Degrees C)

X

Y

Z

Increasing Fan
Speed & Noise

Higher Set Point

Highest Noise Level