what is the difference between C1E and the idle state in CoolnQuiet? Can you still do things which don't require much processing power (ie playing music, word processing)? I'm confused, this Anandtech article says the halt command shuts off the clock signal, so you cannot do anything?http://www.anandtech.com/cpuchipsets/sh ... spx?i=2725
C1E is only invoked if the CPU recieves the HLT signal. This is issued by the OS when there are no instructions to do (think of the idle process in the task manager issuing HLT). Once a Core 2 CPU recieves the HLT, it's clocking down multiplier 6x and a certain minimum VID (desktop 1.163 V, mobile 0.95 V). Once it recieves a non-HLT signal, multiplier and VID go up to standard levels.
EIST is controlled by a OS driver which instructs the CPU. The driver measures the CPU load, then it selects from several steps (up to 6 on my mobile cpu) which one to choose. The lowest EIST multiplier/VID matches exactly the ones of C1E. The other steps are choosen at medium load. EIST keeps the multiplier/VID as low as they are needed.