Low Power Features
2.3
Enhanced Intel SpeedStep® Technology
The processor features Enhanced Intel SpeedStep Technology. Following are the key
features of Enhanced Intel SpeedStep Technology:
•
Multiple voltage and frequency operating points provide optimal performance at
the lowest power.
•
Voltage and frequency selection is software controlled by writing to processor
MSRs:
⎯ If the target frequency is higher than the current frequency, VCC is ramped up
in steps by placing new values on the VID pins and the PLL then locks to the
new frequency.
⎯ If the target frequency is lower than the current frequency, the PLL locks to
the new frequency and the VCC is changed through the VID pin mechanism.
⎯ Software transitions are accepted at any time. If a previous transition is in
progress, the new transition is deferred until the previous transition
completes.
•
•
The processor controls voltage ramp rates internally to ensure glitch free
transitions.
Low transition latency and large number of transitions possible per second:
⎯ Processor core (including L2 cache) is unavailable for up to 10 μs during the
frequency transition.
— The bus protocol (BNR# mechanism) is used to block snooping.
•
Improved Intel® Thermal Monitor mode:
⎯ When the on-die thermal sensor indicates that the die temperature is too high,
the processor can automatically perform a transition to a lower frequency and
voltage specified in a software programmable MSR.
⎯ The processor waits for a fixed time period. If the die temperature is down to
acceptable levels, an up transition to the previous frequency and voltage point
occurs.
⎯ An interrupt is generated for the up and down Intel Thermal Monitor
transitions enabling better system level thermal management.
•
Enhanced thermal management features:
⎯ Digital Thermal Sensor and Out of Specification detection
⎯ Intel Thermal Monitor-1 in addition to Intel Thermal Monitor-2 in case of
unsuccessful Intel Thermal Monitor-2 transition.
Datasheet
17
INTEL [ INTEL ]
