Originally Posted by B!0HaZard
I promise you that EIST + no C-State limit = low idle speeds. C1E won't lower your idle voltages either.
Okay, now I'm a bit confused. I was going to prove to you how C1E is necessary to lower your voltage when at idle as well as allowing EIST to lower your multiplier, but I came across something weird. (The below screenshots are done at stock clocks since my PC won't boot at AUTO voltage @ 4.8Ghz.)
C1E enabled idle:
C1E enabled load:
Now here is where it gets weird, the above are what I expected as I've been trying to get my CPU to downclock on idle with voltages moving accordingly. It wouldn't in the past if voltage was manually set above 1.4v, so I stopped until recently. I've started overclocking using turbo and setting my multi in the turbo section, (which incidentally has lowered my required vcore) but voltages won't drop as it's still above 1.4v. I noticed that removing C1E didn't affect it, so I tried removing the no limit switch - still no change. I completely
turned off C states, and...
C states off, idle:
C states off, load:
I'm not sure what's going on here now as there was a huge difference between having C1E on with C states enabled. I admit that this isn't conclusive, but without C1E, my CPU wouldn't downclock from 4.8Ghz. (Intel SVID also had to be enabled as APS wouldn't do it either.)
What's confusing to me is that C1E is supposed to be low power state per Intel, and C package limit is supposed to be related to the amount of power allowed for each stage of processor use.
Originally Posted by Intel
CPU/Package sleep states
C0 - Active: CPU is on. C0 is the operating state.
C1 - Auto Halt: core clock is off. C1 is a state where the processor is not executing instructions, but can return to an executing state essentially instantaneously. Some processors also support an Enhanced C1 state (C1E) for lower power consumption.
C2 - Stop Clock: core and bus clocks are off. C2 is a state where the processor maintains all software-visible state, but may take longer to wake up.
C3 - Deep Sleep: clock generator is off. C3 is a state where the processor does not need to keep its cache coherent, but maintains other states. Some processors have variations on the C3 state (Deep Sleep, Deeper Sleep, etc.) that differ in how long it takes to wake the processor.
C4 - Deeper Sleep: reduced VCC
DC4 - Deeper C4 Sleep: further reduced VCC
Here's some more information on C states and why this result is a little confusing: Intel C state blog
Note: I have windows set to performance
, so my OS is not downclocking or undervolting. (Something any overclocker should change to keep stability.)