Vol 1

Intel® Xeon® Product 2800/4800/8800 v2 Product Family 59
Datasheet Volume One, February 2014
Thermal Management Specifications
This method includes multiple operating points, each consisting of a specific operating
frequency and voltage. The first operating point represents the normal operating
condition for the processor. The remaining points consist of both lower operating
frequencies and voltages. When the TCC is activated, the processor automatically
transitions to the new lower operating frequency. This transition occurs very rapidly (on
the order of microseconds). Once the new operating frequency is engaged, the
processor will transition to the new core operating voltage by issuing a new SVID code
to the VCC voltage regulator. The voltage regulator must support dynamic SVID steps
to support this method. During the voltage change, it will be necessary to transition
through multiple SVID codes to reach the target operating voltage. The processor
continues to execute instructions during the voltage transition. Operation at the lower
voltages reduces the power consumption of the processor.
A small amount of hysteresis has been included to prevent rapid active/inactive
transitions of the TCC when the processor temperature is near its maximum operating
temperature. Once the temperature has dropped below the maximum operating
temperature, and the hysteresis timer has expired, the operating frequency and
voltage transition back to the normal system operating point via the intermediate
SVID/frequency points. Transition of the SVID code will occur first, to insure proper
operation once the processor reaches its normal operating frequency. Refer to
Figure 4-12 for an illustration of this ordering.
4.2.2.2 Clock Modulation
Clock modulation is performed by alternately turning the clocks off and on at a duty
cycle specific to the processor (factory configured to 37.5% on and 62.5% off for TM1).
The period of the duty cycle is configured to 32 microseconds when the TCC is active.
Cycle times are independent of processor frequency. A small amount of hysteresis has
Figure 4-12. Frequency and Voltage Ordering