Intel BX80571E5300 - Pentium 2.6 GHz Processor, Datasheet

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Thermal Specifications and Design Considerations
82 Datasheet
wide range (2 Kbps to 2 Mbps). The PECI interface on the processor is disabled by
default and must be enabled through BIOS. More information can be found in the
Platform Environment Control Interface (PECI) Specification.
5.3.1.1 T
CONTROL
and TCC activation on PECI-Based Systems
Fan speed control solutions based on PECI utilize a T
CONTROL
value stored in the
processor IA32_TEMPERATURE_TARGET MSR. The T
CONTROL
MSR uses the same offset
temperature format as PECI though it contains no sign bit. Thermal management
devices should infer the T
CONTROL
value as negative. Thermal management algorithms
should utilize the relative temperature value delivered over PECI in conjunction with the
T
CONTROL
MSR value to control or optimize fan speeds. Figure 16 shows a conceptual
fan control diagram using PECI temperatures.
The relative temperature value reported over PECI represents the delta below the onset
of thermal control circuit (TCC) activation as indicated by PROCHOT# assertions. As the
temperature approaches TCC activation, the PECI value approaches zero. TCC activates
at a PECI count of zero.
5.3.2 PECI Specifications
5.3.2.1 PECI Device Address
The PECI register resides at address 30h.
5.3.2.2 PECI Command Support
PECI command support is covered in detail in the Platform Environment Control
Interface Specification. Refer to this document for details on supported PECI command
function and codes.
Figure 16. Conceptual Fan Control Diagram on PECI-Based Platforms