Intel 1.00 GHz YK80542KC0013M User Manual

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This chapter provides a description of the thermal features relating to the Itanium 2 processor.

The Itanium 2 processor has an internal thermal circuit which senses when a certain temperature is 
reached on the processor core. This circuit is used for controlling various thermal states. In 
addition, an on-chip thermal diode is available for use by the thermal sensing device on the 
Itanium 2 processor. 

 shows the relationship between temperature, time, and the thermal 

alert, enhanced thermal management (ETM), and thermal trip points.

 is not intended to show a linear relationship in time or temperature as a processor's 

thermal state advances from one state to the next state when the cooling solution fails to control the 
processor temperature, as this is affected by many factors such as cooling solution performance 
degradation and processor workload variations. 

THRMALERT# is a programmable thermal alert signal which is part of the Itanium 2 processor 
system management feature. THRMALERT# is asserted when the measured temperature from the 
processor thermal diode equals or exceeds the temperature threshold data programmed in the high 
temp (THIGH) or low temp (TLOW) registers on the sensor. Intel recommends using the upper 
temperature reference byte listed in the Processor Information ROM when programming the 
THIGH register (see 

 for more details). This signal can be used by the platform to 

implement thermal regulation features such as generating an external interrupt to tell the operating 
system that the processor core die temperature is increasing.

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Thermal Alert

Thermal Trip

ETM