Everybody jumps on EIST when idle power of intel CPUs is measured. But you people forget about C1E. C1E on my Merom already puts the CPU into multplier 6x and VID 0.95V. EIST does not get further down when enabled.
EIST does not depend on HLT-cmds but on CPU load, so it keeps the FID/VID down in more situations than C1E and also provides steps for medium load. So when a review without EIST surfaces, the next question would be wether C1E is enabled. You can enable/disable C1E in RMClock.

Enabling EIST on my Merom yields 1W less from the wall at idle... Conroe idles at 1600 MHz with C1E. Have a look at this article at section "Intel Core 2: tests". http://www.digit-life.com/articles2/cpu ... core2.html

Intel issued a product change notification PCN 106853-00 introducing a new stepping L2 and lower C1E/EIST idle power consumption for both B2 and L2 from 20-22 down to 10-12 W. Affected cpus:

E6300, E6400 10 W stepping L2 (Allendale!)
E6600, E6700 12 W stepping B2
Xeon 3040, 3050, 3060, 3070 should be affected accordingly

E4300 is mentioned.

source: http://www.heise.de/newsticker/meldung/82671

EDIT: only Allendales get new stepping.

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.