Low Power Features
18
Datasheet
2.3
Extended Low-Power States
Extended low-power states (CXE) optimize for power by forcibly reducing the
performance state of the processor when it enters a package low-power state. Instead
of directly transitioning into the package low-power state, the enhanced package low-
power state first reduces the performance state of the processor by performing an
Enhanced Intel SpeedStep Technology transition down to the lowest operating point.
Upon receiving a break event from the package low-power state, control will be
returned to software while an Enhanced Intel SpeedStep Technology transition up to
the initial operating point occurs. The advantage of this feature is that it significantly
reduces leakage while in the Stop-Grant state.
Note:
Long-term reliability cannot be assured unless all the Extended Low Power States are
enabled.
The processor implements two software interfaces for requesting enhanced package
low-power states: MWAIT instruction extensions with sub-state hints and via BIOS by
configuring IA32_MISC_ENABLES MSR bits to automatically promote package low-
power states to enhanced package low-power states.
Caution:
Extended Stop-Grant must be enab
l
ed via the BIOS
for the processor to
remain within specification. As processor technology changes, enabling the
extended low power states becomes increasingly crucial when building computer
systems. Maintaining the proper BIOS configuration is key to reliable, long-term
system operation. Not complying to this guideline may affect the long-term reliability of
the processor.
Caution:
Enhanced Intel SpeedStep Technology transitions are multistep processes
that require clocked control. These transitions cannot occur when the processor is in
the Sleep or Deep Sleep package low-power states since processor clocks are not
active in these states. The transition to the lowest operating point or back to the
original software-requested point may not be instantaneous. Furthermore, upon very
frequent transitions between active and idle states, the transitions may lag behind the
idle state entry resulting in the processor either executing for a longer time at the
lowest operating point or running idle at a high operating point. Observations and
analyses show this behavior should not significantly impact total power savings or
performance score while providing power benefits in most other cases.
Summary of Contents for BX80532PG3200D
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Page 10: ...Introduction 10 Datasheet...
