Intel Core 2 Extreme QX6850 BX80569QX6850 User Manual

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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 processor 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. 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 MSRs 

(Model Specific Registers), thus eliminating chipset dependency.

— If the target frequency is higher than the current frequency, V

CC

 is incremented 

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

CC

 is then decremented in steps (-12.5 mV) by 

changing the target VID through the VID signals.