865G Datasheet, PDF (181/249 Pages) Intel Corporation – Intel 865G/865GV Graphics and Memory Controller Hub

Functional Description
Note: The use of external sensors that include an internal pull-up resistor on the open-drain thermal trip
output is discouraged; however, it may be possible depending on the size of the pull-up and the
voltage of the sensor.
Figure 14. Platform External Sensor
V
EXTTS#
R⁽¹⁾
Processor
GMCH
5.7.1.1
THERM#
TS
TS
Intel^® ICH5
SMBus
SMBdata
SMBclock
NOTE:
1. External pull-up R is associated with the voltage rail of the GMCH input.
External Thermal Sensor Usage Model
There are several possible usage models for an external thermal sensor:
• External sensor(s) used for characterization only, not for normal production
• Sensor on the DIMMs for temperature in OEM platform and use the results to permanently set
read throttle values in the BIOS
• Sensor on the GMCH for temperature in OEM platform and use the results to permanently set
write throttle values in the BIOS
• External sensor(s) used for dynamic temperature feedback control in production releases
• Sensor on DIMMs, which can be used to dynamically control read throttling
• Sensor on GMCH, which can be used to dynamically control write throttling
The advantage of the characterization model is the Bill-Of-Material (BOM) cost, whereas the
potential advantage of the dynamic model is that retail customers may be able to experience higher
peak performance since the throttle values are not forced to encompass worse case environmental
conditions.
Characterization tools (e.g., CTMI and Maxband) can be made to work either with external or
internal sensors.
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Intel^® 82865G/82865GV GMCH Datasheet