Intel Quad-Core Xeon Datasheet page 108

support this feature will be provided in future releases of the Quad-Core Intel® Xeon®
Processor 5300 Series NDA Specification Update when available.
Enhanced Intel SpeedStep Technology creates processor performance states (P-states)
or voltage/frequency operating points. P-states are lower power capability states within
the Normal state as shown in
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 5300 Series have hardware logic that coordinates
the requested voltage (VID) between the processor cores. The highest voltage that is
requested from the four 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.
See the Conroe and Woodcrest Processor Family BIOS Writer's Guide for specific
information to enable and configure Enhanced Intel SpeedStep Technology in BIOS.
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Figure 7-1. Enhanced Intel SpeedStep Technology
is then decremented in steps (-12.5 mV) by
CC
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Quad-Core Intel® Xeon® Processor 5300 Series Datasheet
Features
is incremented
CC