182
Intel
82865G/82865GV GMCH Datasheet
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.
NOTE:
1. External pull-up R is associated with the voltage rail of the GMCH input.
5.7.1.1
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.
Figure 14. Platform External Sensor
Processor
GMCH
EXTTS#
Intel
ICH5
SMBus
D
D
TS
TS
R
(1)
V
THERM#
SMBdata
SMBclock