If your looking for info on this another name for CxE Function is "C1E Support", "C-States/C-Modes" and also "Enhanced Halt State".
C1E (Enhanced Halt State): C1E is the simpler of the two components. It can be enabled or disabled in the BIOS, and performs independently of the operating system. C1E has two configurations - idle, and load. When CPU usage is relatively low, this feature lowers your processor's multiplier to its lowest setting (12x for i7) and slightly lowers its vCore. During a CPU-intensive application, it will raise the multipler to its maximum value, and will provide a small boost in vCore to compensate. In our example, C1E will make your processor run at
either 12x or 21x the BClock.
Here is a good article that goes more in-depth into the different halt States, C1E is one option but you also have options like C6.
link:
http://www.hardwaresecrets.com/article/611
Intel SpeedStep is similar to CxE Function (Enhanced Halt State) EIST (Enhanced Intel SpeedStep Technology): This is a very robust feature and has a wide variety of power-saving capabilities. Like its simpler cousin, EIST can affect both your CPU's voltage and it's multiplier - however, it has many more levels of configuration. Instead of a simple "slow or fast" setting, SpeedStep can utilize all of the available multipliers. In our example case, EIST will allow your processor to
run with a multiplier of 12, 13, 14,...,21, and chooses which one to use based on how much demand your CPU is under. EIST is controlled by Windows, and utilizes the different "power schemes" you may have seen in your control panel.
Its good to have them working together, Intel SpeedStep taking care of the multiplier/vCore and CxE Function putting the different parts of the i7 CPU (Core, Cache) into different low power states, C6 even going as far as effectively turning off unused parts of the CPU (this only ahppens on i7, before that all the CPU had to be turned off not just parts like the i7).
post edited by Moltenlava - 2010/03/31 03:28:50