C State Name			  Purpose
C0	Operational status	  The processor is working to its full potential
C1	Stop/Halt		  Stops the internal clocks of the processor, but the interfaces and APICs continue to function.
C1E	Improved stop		  Stops all internal clocks of the software processor.
C2	Stop the clock		  Stops the internal and external clocks of the CPU by hardware.
C2	Detention permit	  Stops the internal and external clocks of the CPU by hardware. The interfaces and APICs continue to work.
C2E	Extended detention permit Stops the main clocks and also reduces the CPU voltage to reduce power consumption. Interfaces and APICs continue to work.
C3	Suspension		  Stops all internal clocks of the CPU.
C3	AltVID			  Stops all internal clocks and lowers voltage.
C3	Deep suspension		  Stops all internal and external clocks of the CPU.
C4	Deep suspension		  Lowers the CPU voltage.
C4E/C5	Enhanced deep suspension  Lowers the voltage even further and turns off the memory cache.
C6	Deep shutdown		  Reduces the CPU voltage to zero.
C7	Deep energy saving	  The CPU flushes the L3 cache and cuts its power. The system agent power is also removed.
C7s				  Substate in which the L3 cache is flushed suddenly rather than in stages. I / O devices are put into energy saving.
C8				  The L3 cache is flushed and power to the PLL is removed.
C9				  The VCC input voltage is minimized.
C10				  The CPU shuts down completely.