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SpeedStep vs Turbo Mode vs C-STATE vs C1E

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  • CPUs
  • Overclocking
  • Intel
  • Turbo Boost
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July 29, 2012 3:19:44 PM

I am seeking an answer with no Overclocking in mind.

Enhanced Intel SpeedStep® Technology http://www.intel.com/cd/channel/reseller/asmo-na/eng/20...

Intel® Turbo Boost Technology http://www.intel.com/content/www/us/en/architecture-and...

C-state architecture http://www.intel.com/technology/itj/2006/volume10issue0...

How SpeedStep and Turbo Mode works in relation to C1E and C-STATE? What should be enabled and what should not, and why?








More about : speedstep turbo mode state c1e

a c 139 à CPUs
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July 29, 2012 3:22:52 PM

all for reducing power consumption and heat generation
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July 29, 2012 3:46:15 PM

jay_nar2012 said:
Speedstep underclocks the CPU when its idle or near idle.
Turbo overclocks the CPU when performance is needed.
This might help alittle- http://www.masterslair.com/should-you-overclock-with-sp...


Thank you for the article! It explains the relations between SpeedStep and C1E, but it doesn´t say a lot about C-STATE.
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July 29, 2012 5:22:43 PM

Thank you for the link!

A friend of mine said that when Turbo Boost mode is on, and C-state is enabled, then just one core goes over speed. On the other hand, if C-state is disabled, then all cores go over speed -- is that correct? Anyone?
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a c 109 à CPUs
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July 29, 2012 6:02:59 PM

You need adobe reader as it is a .pdf link.
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July 29, 2012 6:06:31 PM

C1E does not kick in until you boot into WINDOWS, that's why in BIOS your temperatures are a bit higher because the processor is on a slight load.
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July 29, 2012 8:40:23 PM

amuffin said:
C1E does not kick in until you boot into WINDOWS, that's why in BIOS your temperatures are a bit higher because the processor is on a slight load.


I have no temperatures issues. It is just an info I´d like to know.
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July 29, 2012 8:44:59 PM

jay_nar2012 said:
You need adobe reader as it is a .pdf link.


I have an updated Adobe reader installed, tough for some reason it freezes the browser (Firefox).
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a c 109 à CPUs
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July 29, 2012 8:47:34 PM

Easier to use IE to open .pdf only...
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July 29, 2012 9:05:29 PM

jay_nar2012 said:
Easier to use IE to open .pdf only...


Thanks! I opened it through IE.
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July 29, 2012 9:09:26 PM

jay_nar2012 said:
Could be possible so that power isn't wasted on the other cores when they aren't needed.
http://download.intel.com/design/processor/applnots/320...



From what I got just the actived cores (C0 and C1) go over speed while C-State is ON.

I still want to confirm that if C-State is OFF then all cores go over speed.
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July 29, 2012 9:09:42 PM

jemm said:
Thanks! I opened it through IE.


No problem.
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a c 161 à CPUs
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July 29, 2012 10:25:01 PM

Posting pdfs may confuse people. So I will just answer this in simple terms.

Enable them all. C-states and speedstep has no affect on turbo.

You seem to be confused what c-states are. C0 and C1 are not core numbers they are states, hence the name c-states. C-states are different states the cpu goes in (is it at on, off, sleeping, etc). So you can't just say c-states on or off, you need to say which ones you disabled.
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July 29, 2012 10:42:20 PM

k1114 said:
Posting pdfs may confuse people. So I will just answer this in simple terms.

Enable them all. C-states and speedstep has no affect on turbo.

You seem to be confused what c-states are. C0 and C1 are not core numbers they are states, hence the name c-states. C-states are different states the cpu goes in (is it at on, off, sleeping, etc). So you can't just say c-states on or off, you need to say which ones you disabled.


I am not confusing anything here.

My browser (Firefox) opens any pdf.file without a problem. It was just one link it didn´t work.

When any core is in C0 or C1 state they are considered by the system as Active Cores. Sorry but C-State has indeed effect on turbo. See below from the link above.

Intel® Turbo Boost technology provides the Core i7 the capability of maximizing core frequency while ensuring that the processor does not go above the upper-limits of
temperature, power, and current. When lower power-consuming applications execute on a subset of active cores (cores in core C0 or core C1) with inactive cores (cores in core C3 or core C6) present in the package, the applications may take advantage of the additional power headroom provided by the inactive cores in the form of increased core frequency (http://impact.asu.edu/cse591sp11/Nahelempm.pdf).
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July 29, 2012 10:45:10 PM

jemm said:
I am not confusing anything here.

My browser (Firefox) opens any pdf.file without a problem. It was just one link it didn´t work. When any core is in C0 or C1 state they are considered by the system as Active Cores.

Sorry but C-State indeed has effect on turbo. See below from the link above.

Intel® Turbo Boost technology provides the Core i7 the capability of maximizing core frequency while ensuring that the processor does not go above the upper-limits of
temperature, power, and current. When lower power-consuming applications execute on a subset of active cores (cores in core C0 or core C1) with inactive cores (cores in core C3 or core C6) present in the package, the applications may take advantage of the additional power headroom provided by the inactive cores in the form of increased core frequency (http://impact.asu.edu/cse591sp11/Nahelempm.pdf).


I see you,ve found your answer?
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July 29, 2012 10:51:27 PM

Not yet, though the links you provided helped a lot.

What exactly I want to know is if all cores go over frequency when C-State is OFF.
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Best solution

a c 109 à CPUs
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July 29, 2012 10:56:36 PM

So basically all cores are controlled as a whole not separately...
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July 30, 2012 12:04:00 AM

Yes, it seems to be case when C-State is OFF.
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July 30, 2012 12:30:22 AM

So your questions have been answered?
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July 30, 2012 2:00:57 AM

Yeap! Thank you!
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July 30, 2012 2:00:59 AM

Best answer selected by jemm.
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July 30, 2012 2:12:02 AM

jemm said:
I am not confusing anything here.

My browser (Firefox) opens any pdf.file without a problem. It was just one link it didn´t work.

When any core is in C0 or C1 state they are considered by the system as Active Cores. Sorry but C-State has indeed effect on turbo. See below from the link above.

Intel® Turbo Boost technology provides the Core i7 the capability of maximizing core frequency while ensuring that the processor does not go above the upper-limits of
temperature, power, and current. When lower power-consuming applications execute on a subset of active cores (cores in core C0 or core C1) with inactive cores (cores in core C3 or core C6) present in the package, the applications may take advantage of the additional power headroom provided by the inactive cores in the form of increased core frequency (http://impact.asu.edu/cse591sp11/Nahelempm.pdf).


What this is saying is that the actice cores go to an even higher speed because there are inactive cores. If you understand how turbo works; it is dependent on how many cores are being used. For a i7-2600k the highest turbo is 3.8ghz with 1 core, 3.7 for 2 cores, 3.6 for 3 cores and 3.5 for 1 core. C-states does not affect turbo, rather the cores can be in an idle state while the others are in c0 state (full speed state). This is what I meant in pdfs confusing people; being confused by the terminology in the pdf as most people are not technically knowledgeable to understand what is being said.
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