Intel Xeon X3440 BX80605X3440 User Manual

Thermal/Mechanical Specifications and Design Guidelines

53

The sensor based thermal specification presents opportunities for the system designer 
to optimize the acoustics and simplify thermal validation. The sensor based 
specification uses the Digital Thermal Sensor information accessed using the PECI 
interface.

This chapter will review thermal solution design options, fan speed control design 
guidance and implementation options and suggestions on validation both with the TTV 
and the live die in a shipping system.

Create a thermal specification that meets the following requirements:

• Use Digital Thermal Sensor (DTS) for real-time thermal specification compliance.
• Single point of reference for thermal specification compliance over all operating 

conditions.

• Does not require measuring processor power and case temperature during 

functional system thermal validation.

• Opportunity for acoustic benefits for DTS values between T

CONTROL

 and -1.

Thermal specifications based on the processor case temperature have some notable 
gaps to optimal acoustic design. When the ambient temperature is less than the 
maximum design point, the fan speed control system (FSC) will over cool the processor. 
The FSC has no feedback mechanism to detect this over cooling, this is shown in the 
top half of 

. 

The sensor based specification will allow the FSC to be operated at the maximum 
allowable silicon temperature or T

J

 for the measured ambient. This will provide optimal 

acoustics for operation above T

CONTROL

. See lower half of