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What is the difference between C1E and EIST

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  • CPUs
  • BIOS
  • Gigabyte
Last response: in CPUs
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November 7, 2006 1:21:15 PM

Hello,

In my mother Gigabyte GA-945GM-S2 bios I see C1E and EIST.

Can I know what is the difference between the two?

Rgds

More about : difference c1e eist

November 7, 2006 1:24:25 PM

C1E is an advance halt state, and EIST is an acronym for Enhanced Intel Speedstep Technology.
November 7, 2006 1:25:25 PM

http://techreport.com/reviews/2005q1/pentium4-600/index...

Give it a read... here's the pertinent info:

Quote:
C1E enhanced halt state — Introduced in the Pentium 4 500J-series processors, the C1E halt state replaces the old C1 halt state used on the Pentium 4 and most other x86 CPUs. The C1 halt state is invoked when the operating system's idle process issues a HLT command. (Windows does this constantly when not under a full load.) Entering halt state, which is a lower-power state, will cut a CPU's power consumption and heat production. Intel's new C1E halt state is also invoked by the HLT command, but it turns down the entire CPU's clock frequency (via multiplier control) and voltage in order to work its mojo. This more robust halt state requires significantly less power than the old C1 implementation.
C1E halt cranks the CPU bus multiplier down to its lowest possible level on the 600-series processors, which is 14X, so a P4 660 processor with the C1E halt state active actually runs at 2.8GHz. I believe that C1E halt is also a binary condition invoked by the HLT command; it's either on or it's off.


Enhanced SpeedStep — SpeedStep also modulates the CPU clock speed and voltage according to load, but it is invoked via another mechanism. The operating system must be aware of SpeedStep, as must the system BIOS, and then the OS can request frequency changes via ACPI. SpeedStep is more granular than C1E halt, because it offers multiple rungs up and down the ladder between the maximum and minimum CPU multiplier and voltage levels.
Intel cites its mobile products when talking about SpeedStep, which is apt but not entirely helpful because it conjures up images of the Pentium M processor, a very different beast. The Pentium 4 doesn't contain most of the heroic power-saving measures of the Pentium M.


Speed Step is a better version of enhance halt state... Think of halt as a toy car, forward and stop, and think of Speed Step as a car with a transmission, Park, and then gears 1-5...
Related resources
November 7, 2006 1:27:49 PM

You're a minute late but you do come bearing analogies.
November 7, 2006 1:29:28 PM

Car analogies are always welcome!
November 7, 2006 1:33:23 PM

Thanks a lot for a comprehensive reply.

Does this mean that I can disable one of the two through the bios, possibly C1E.

My E6300 is at 266x6 = 1596 at idle.
Will the speedstep bring it down further?

Or the XP implementation of speedstep is sluggish.
November 7, 2006 1:35:13 PM

At that speed what is your VCore reading?
November 7, 2006 1:43:04 PM

Quote:
Hello,

In my mother Gigabyte GA-945GM-S2 bios I see C1E and EIST.

Can I know what is the difference between the two?

Rgds


Its kinda weird (now that I think about it) to see both features like that in the bios.

So.. I'm guessing at this, is the C1E more used at what the MB supports on the low end cpu, and EIST for the newer?

I just don't seem to understand if or why both would be used for the E6xxx procs.
November 7, 2006 2:02:49 PM

Seems to me the C1E is used if you put a conroe in something that doesn't support EIST (do non Intel chipsets support it? Do they support C1E instead?)...

Taking a shot in the dark, anyone have more info on this?
November 7, 2006 2:25:06 PM

Quote:
Hello,

In my mother Gigabyte GA-945GM-S2 bios I see C1E and EIST.

Can I know what is the difference between the two?

Rgds


i see same of the people arround already gave the answer ...well
C1e is an enhanced hardware sleep state..while EIST stands for enhanced intel speed step tehnology...

the diference between the two of them are that EIST needs os support while c1e won`t need ...

similar tehnologies are cool and quiet (amd), tm (intel) and tm2(intel)
November 7, 2006 2:35:30 PM

Quote:
At that speed what is your VCore reading?


CPU Core fluctuating between 1.152 to 1.280 volts according to everest
November 7, 2006 2:35:40 PM

In order to run a C2D, you need the right chipset and VMR? So I would assume that it would have EIST.

Looking at the feature of C2D, I don't see C1E listed in their charts:

Intel® Core™2 Duo Processor

and

List of Intel Core 2 microprocessors - Wikipedia

I mean both do the same thing, though the EIST does abit more with core voltage. And it seems C1 is for really older cpus, the C1E for 600 P4 series.

So.. I guess that is what I'm coming up in assuming those features are for those particular CPU a MB supports.
November 7, 2006 2:50:19 PM

Well Intel specifies your VCore at 0.850V-1.3525V. So I do believe that your processor speed can drop even more when idling.
November 7, 2006 4:00:55 PM

Gawd.. I think I'm confusing myself.

Since the OP says both are present in the bios, are they both needed in order to work properly?

It seems I'm finding that theres less info on C1E, specifically when I try to find it as a feature for Pentium 600 series.

I'm even finding Pentium 4 631-651 listing EIST as the feature, yet C1E is no where to be found.

I guess where I'm confused the most is that both seem to do the same thing, although the EIST affects the vcore settings.

So are those features like an extention of one another?
November 7, 2006 4:08:58 PM

Some BIOS have the C1E as a feature. Some do not. *shrug*
November 7, 2006 4:11:55 PM

I disabled C1E in BIOS and expected speedstep to take over.

But it did not and my CPU was UP at 1.86GHz.

When I set my power profile to laptop the multiplier was brought down to 6 to make the CPU speed 266*6 = 1596 MHz.

So I think speedstep is just using CPU multiplier and not dropping the VCore but I am not sure abt other settings of speedstep in windows XP

Is there a way to drop Vcore or a better way of using speedstep?
November 7, 2006 4:44:38 PM

Hmmmm... I think I rmr reading that speedstep is only used when in laptop mode, whereas C1E would probably be more used when in desktop power profile? It would make more sense since laptops still need to conserve power while delivering performance, whereas comps could be slow while just surfing and typing docs, whereas they go full blast when encoding and gaming...

A good a guess as any other...
November 7, 2006 4:56:44 PM

Well, I did find this info:

Intel secretly changes the rules

Quote:
What change did Intel introduce ? Basically, the TSC may not be incremented according to the CPU internal clock speed. Some explanations : The Prescott Pentium 4, since its F41 revision, uses a clock modulation mechanism in order to reduce its consumption : the C1E state. This mechanism allows to reduce the CPU multiplier down to 14x when idling, namely when the CPU is not used. So doing, it reduces the consumption and the dissipated heat. Then, the 6xx Pentium 4 introduced a more advanced clock modulation mechanism, the EIST, that changes the CPU clock multiplier and voltage according to the CPU utilization.


So would that be more specific for C1E on CPU's before the P4 6xx?
November 7, 2006 4:58:55 PM

Quote:
Hmmmm... I think I rmr reading that speedstep is only used when in laptop mode, whereas C1E would probably be more used when in desktop power profile? It would make more sense since laptops still need to conserve power while delivering performance, whereas comps could be slow while just surfing and typing docs, whereas they go full blast when encoding and gaming...

A good a guess as any other...


I agree, my testing showed the same thing, it also seems that speedstep may not change the vcore, but just the multiplier and set to lowest possible value which happens to be 6 for E6300.
November 7, 2006 5:05:07 PM

Do you have a VCore menu in your BIOS? Because if you don't, I would worry to much. And I also wouldn't recommend trying Clockgen unless you're damn sure what PLL you have. Otherwise you could seriously screw up stuff (I tried it on a Dell Dimension and a HP Pavilion and had both do a total freeze on me)
November 7, 2006 5:43:34 PM

Quote:
Do you have a VCore menu in your BIOS? Because if you don't, I would worry to much. And I also wouldn't recommend trying Clockgen unless you're damn sure what PLL you have. Otherwise you could seriously screw up stuff (I tried it on a Dell Dimension and a HP Pavilion and had both do a total freeze on me)


I do not have a VCore menu in my bios, this being the entry level board.

What is PLL?
November 7, 2006 5:46:44 PM

Then the chances of you lowering the VCore are slim to none. These OC programs are only an extension of the BIOS and do not act as a substitute for the BIOS.

But to answer your question, a PLL is a phase-locked loop, a closed-loop feedback control system that generates and outputs a signal in relation to the frequency and phase of an input ("reference") signal. A phase-locked loop circuit responds to both the frequency and the phase of the input signals, automatically raising or lowering the frequency of a controlled oscillator until it is matched to the reference in both frequency and phase.
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