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Figure 14. Package C-State Entry and Exit
C0
C1
C6
C7
C3
Package C0 State
This is the normal operating state for the processor. The processor remains in the
normal state when at least one of its cores is in the C0 or C1 state or when the
platform has not granted permission to the processor to go into a low-power state.
Individual cores may be in lower power idle states while the package is in C0 state.
Package C1/C1E State
No additional power reduction actions are taken in the package C1 state. However, if
the C1E sub-state is enabled, the processor automatically transitions to the lowest
supported core clock frequency, followed by a reduction in voltage.
The package enters the C1 low-power state when:
• At least one core is in the C1 state.
• The other cores are in a C1 or deeper power state.
The package enters the C1E state when:
• All cores have directly requested C1E using MWAIT(C1) with a C1E sub-state hint.
• All cores are in a power state deeper than C1/C1E state; however, the package
low-power state is limited to C1/C1E using the PMG_CST_CONFIG_CONTROL MSR.
• All cores have requested C1 state using HLT or MWAIT(C1) and C1E auto-
promotion is enabled in IA32_MISC_ENABLES.
No notification to the system occurs upon entry to C1/C1E state.
Power Management—Processor
Desktop 4th Generation Intel
®
Core
™
Processor Family, Desktop Intel
®
Pentium
®
Processor Family, and Desktop Intel
®
Celeron
®
Processor Family
December 2013 Datasheet – Volume 1 of 2
Order No.: 328897-004 57