Datasheet 103
Balanced Technology Extended (BTX) Type I Boxed Processor Specifications
If the boxed processor TMA 4-pin connector is connected to a 4-pin motherboard header and the
motherboard is designed with a fan speed controller with PWM output (see Table 8 -1) and remote
thermal diode measurement capability, the boxed processor will operate as described in the
following paragraphs.
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 (TDIODE). 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 a combination of actual processor temperature and thermistor temperature.
If the new 4-pin active TMA solution is connected to an older 3-pin baseboard processor fan
header, it will default back to a thermistor controlled mode allowing compatibility with existing 3-
pin baseboard designs. Under thermistor controlled mode, the fan RPM is automatically varied
based on the Tinlet 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® Pentium® D Processor and Intel® Pentium® Processor Extreme Edition 840 Thermal and
Mechanical Design Guidelines.
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