Intel 830 Datenbogen

96

If the boxed processor fan heatsink 4-pin connector is connected to a 4-pin motherboard header and 
the motherboard is designed with a fan speed controller with PWM output (For details on 
CONTROL, see 

) and remote thermal diode measurement capability the boxed processor 

will operate as follows:

As processor power has increased the required thermal solutions have generated increasingly more 
noise. Intel has added an option to the boxed processor that allows system integrators to have a 
quieter system in the most common usage.

The 4th wire PWM solution provides better control over chassis acoustics. This is achieved by 
more accurate measurement of processor die temperature through the processor's temperature 
diode (T

DIODE

). Fan RPM is modulated through the use of an ASIC located on the motherboard 

that sends out a PWM control signal to the 4th pin of the connector labeled as CONTROL. The fan 
speed is based on the actual processor temperature instead of internal ambient chassis 
temperatures.

If the new 4-pin active fan heat sink solution is connected to an older 3-pin baseboard processor fan 
header, it will default back to a thermistor controlled mode. This allows compatibility with existing 
3-pin baseboard designs. Under thermistor controlled mode, the fan RPM is automatically varied 
based on the T

inlet

 temperature measured by a thermistor located at the fan inlet.

For more details on specific motherboard requirements for 4-wire based fan speed control, see the 
Intel

Mechanical Design Guidelines.

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