Frequency And Voltage Ordering - Intel Core i7 Extreme Edition Datasheet

Thermal Specifications
6.2.2.1 Frequency/VID Control
When the Digital Temperature Sensor (DTS) reaches a value of 0 (DTS temperatures
reported via PECI may not equal zero when PROCHOT# is activated, see
further details), the TCC will be activated and the PROCHOT# signal will be asserted.
This indicates the processors' temperature has met or exceeded the factory calibrated
trip temperature and it will take action to reduce the temperature.
Upon activation of the TCC, the processor will stop the core clocks, reduce the core
ratio multiplier by 1 ratio and restart the clocks. All processor activity stops during this
frequency transition which occurs within 2 us. Once the clocks have been restarted at
the new lower frequency, processor activity resumes while the voltage requested by the
VID lines is stepped down to the minimum possible for the particular frequency.
Running the processor at the lower frequency and voltage will reduce power
consumption and should allow the processor to cool off. If after 1ms the processor is
still too hot (the temperature has not dropped below the TCC activation point, DTS
still = 0 and PROCHOT is still active) then a second frequency and voltage transition will
take place. This sequence of temperature checking and Frequency/VID reduction will
continue until either the minimum frequency has been reached or the processor
temperature has dropped below the TCC activation point.
If the processor temperature remains above the TCC activation point even after the
minimum frequency has been reached, then clock modulation (described below) at that
minimum frequency will be initiated.
There is no end user software or hardware mechanism to initiate this automated TCC
activation behavior.
A small amount of hysteresis has been included to prevent rapid active/inactive
transitions of the TCC when the processor temperature is near the TCC activation
temperature. Once the temperature has dropped below the trip temperature, and the
hysteresis timer has expired, the operating frequency and voltage transition back to
the normal system operating point via the intermediate VID/frequency points.
Transition of the VID code will occur first, to insure proper operation as the frequency is
increased. Refer to
Figure 6-3.

Frequency and Voltage Ordering

f f
MAX MAX
f f
1 1
f f
2 2
VIDf VIDf
MAX MAX
VIDf VIDf
VIDf VIDf
Datasheet
Table 6-3 for an illustration of this ordering.
1 1
2 2
Temperature Temperature
Frequency Frequency
VID VID
PROCHOT# PROCHOT#
Section 6.3 for
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