Intel E5410 - Cpu Xeon Quad Core 2.33Ghz Fsb1333Mhz 12M Lga771 Tray Datasheet page 102

Enhanced Intel SpeedStep Technology creates processor performance states (P-states)
or voltage/frequency operating points which are lower power capability states within
the Normal state (see
states). Enhanced Intel SpeedStep Technology enables real-time dynamic switching
between frequency and voltage points. It alters the performance of the processor by
changing the bus to core frequency ratio and voltage. This allows the processor to run
at different core frequencies and voltages to best serve the performance and power
requirements of the processor and system. The Quad-Core Intel® Xeon® Processor
5400 Series has hardware logic that coordinates the requested voltage (VID) between
the processor cores. The highest voltage that is requested for either of the processor
cores is selected for that processor package. Note that the front side bus is not altered;
only the internal core frequency is changed. In order to run at reduced power
consumption, the voltage is altered in step with the bus ratio.
The following are key features of Enhanced Intel SpeedStep Technology:
• Multiple voltage/frequency operating points provide optimal performance at
reduced power consumption.
• Voltage/frequency selection is software controlled by writing to processor MSR's
(Model Specific Registers), thus eliminating chipset dependency.
— If the target frequency is higher than the current frequency, V
in steps (+12.5 mV) by placing a new value on the VID signals and the
processor shifts to the new frequency. Note that the top frequency for the
processor can not be exceeded.
— If the target frequency is lower than the current frequency, the processor shifts
to the new frequency and V
changing the target VID through the VID signals.
102
Figure 7-1 for the Stop Clock State Machine for supported P-
is then decremented in steps (-12.5 mV) by
CC
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Features
is incremented
CC