Differences between C1E, C3/C6 and EIST ~ sandy bridge

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Aaron_ATX

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I've searched the forums and done some testing on my rig, but I still have some questions as to the exact functions of these options.

My mobo manual has them all listed as basically word for word the same thing....

Previously I had C1E disabled, C3/C6 enabled, and EIST disabled.

at 47x100 with +0.60 DVID and load line calibration set to 1, and the powersaving settings set to as above here is what I find:

Idle : According to CPU-Z 1.59 ~ 16x100 and vcore is .948 to .960 (vcore read with eazytune 6. no other program seems to read it correctly) Eazytune states that the core speed is 47x100 still.

Load: CPU-Z ~ 47x100 and 1.392 to 1.404 vcore. Eazytune states the exact same.

If I enable all powersaving options, C1E C3/C6 and EIST, the only real difference I find is that Eazytune shows my multiplier dropping as low as 1, and bounces in between 1 and 47 depending on what load is on the CPU. Vcore moves around a bit more but doesnt go over 1.4ish under full load.

CPU-Z just sits at either 16x100 or 47x100.

I have read posts stating that harddrive performance has suffered for some folks with c1e disabled....I have yet to do any benching to confirm that.

For now I am just going to leave it all on unless I suspect it is screwing with my o/c's stability.

Can anyone shed some light on the specific differences between these options? Or a link if I somehow missed it..... thanks!
 
ignore what eztune says.

C1E is power saving (Speedstep) handled directly by the CPU itself.
EIST is the same as C1E, except it's handled by the operating system instead of the CPU.
If you enable C1E and set windows 7 to max performance, it will still downclock to 1600 mhz, because the cpu/motherboard is handling the power saving.
If you enable EIST and set windows to max performance, it will act the same as if EIST was disabled (not downclock).
 
C3/C6 are deeper sleep states, if I remember correctly. Unless you are having problems, you can just leave them all on.
 
Falkentyne said:
ignore what eztune says.

C1E is power saving (Speedstep) handled directly by the CPU itself.
EIST is the same as C1E, except it's handled by the operating system instead of the CPU.
If you enable C1E and set windows 7 to max performance, it will still downclock to 1600 mhz, because the cpu/motherboard is handling the power saving.
If you enable EIST and set windows to max performance, it will act the same as if EIST was disabled (not downclock).
Click to expand...

Thank you, nice and concise. Based on that, i believe i'd rather disable EIST and let the processor handle itself.
 
Aaron_ATX said:
Thank you, nice and concise. Based on that, i believe i'd rather disable EIST and let the processor handle itself.
Click to expand...

Just leave it enabled, there really is no reason not too.

SonDa5 said:
What type of problems?
Click to expand...

If I recall correctly, problems where the system would crash if it was left idle for some length of time. The system would try to go into a low-power mode and lock up. The problems may have been fixed with a BIOS update though, as I remember it mostly being a problem when the SB chips first came out.
 
Forceman said:
If I recall correctly, problems where the system would crash if it was left idle for some length of time. The system would try to go into a low-power mode and lock up. The problems may have been fixed with a BIOS update though, as I remember it mostly being a problem when the SB chips first came out.
Click to expand...
I had that problem on the few P67 (2xP8P67 Pro and Sabertooth P67) boards I had. Eventually, I RMA'd my memory and that seemed to fix it.

Anyway, if you aren't having issues with everything enabled, I would leave them as such.
 
What do you do if you want your processor to idle at a low frequency but clock up to maximum the instant there's any sort of load and remain there until that load is gone?

I've noticed that with every single one of these frequency-modulating techniques, the frequency is constantly bouncing around. If I'm doing some moderately-intensive task (transferring files, installing, etc) that uses about 25% of the CPU, the frequency stays well below maximum. But if I force maximum frequency, the task takes less than half the time!

That is retarded. Is there any way to do what I underlined above? Currently I just keep it at max frequency all the time so I don't have to deal with a 2 GHz processor most of the time.
 
wabbitseason said:
What do you do if you want your processor to idle at a low frequency but clock up to maximum the instant there's any sort of load and remain there until that load is gone?

I've noticed that with every single one of these frequency-modulating techniques, the frequency is constantly bouncing around. If I'm doing some moderately-intensive task (transferring files, installing, etc) that uses about 25% of the CPU, the frequency stays well below maximum. But if I force maximum frequency, the task takes less than half the time!

That is retarded. Is there any way to do what I underlined above? Currently I just keep it at max frequency all the time so I don't have to deal with a 2 GHz processor most of the time.
Click to expand...

It is dynamically changing the clock speed (even faster than CPU-z or whatever is reporting it) to meet the changing load. This is as designed. If you don't want it to do that, but would rather run at 4.5 or whatever all the time, then just disable EIST and C1E.

I find it hard to believe that you are halving your file transfer time based simply in changing your CPU to maximum frequency as that task are not CPU dependent. Can you show some benchmarks for that?
 
The clock speed is changing to meet the changing load, yes. But when I can make something go twice as fast simply by forcing a higher clock speed, that means that that frequency modulation logic is completely screwy. Clearly the CPU is saying "this is a peice of cake, so I'm just going to clock down and do it slow-like".

I don't have any benchmarks to provide at this point, but that isn't remotely the issue anyway.
 
I keep speedstep and c1e enabled but turn off the C3, c6 report, or any C package power saving. Using offset voltage control i've noticed my idle voltages getting really low with those enabled
 
wabbitseason said:
The clock speed is changing to meet the changing load, yes. But when I can make something go twice as fast simply by forcing a higher clock speed, that means that that frequency modulation logic is completely screwy. Clearly the CPU is saying "this is a peice of cake, so I'm just going to clock down and do it slow-like".

I don't have any benchmarks to provide at this point, but that isn't remotely the issue anyway.
Click to expand...

It very much is the issue. You are claiming that the power saving features, which have been incorporated in all CPUs for years now, are causing you a 50% reduction in performance - something which no one else seems to have noticed. So benchmarks would be nice - I'm sure a lot of people would be interested in finding out if disabling speedstep does have a significant performance impact. Perhaps something else is causing your slowdowns? Are you writing to a compressed or encrypted drive?
 
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iplayCS said:
I keep speedstep and c1e enabled but turn off the C3, c6 report, or any C package power saving. Using offset voltage control i've noticed my idle voltages getting really low with those enabled
Click to expand...

Same here. Except I have manual voltages (never bothered with offsets, too much headache to figure out proper voltages) but Speedstep and C1E is enabled, rest is off. If I have C3 and C6 on (and I mean Enabled, not on Auto which means disabled when overclocking), it makes MPC-HC behave wierdly, it makes it unresponsive once going fullscreen. Keyboard presses have a huge delay, trouble showing the bar when I move the mouse down etc... its like its choking on something.

Bizarre reall. How the hell can a powersaving functions screw up a mere media player so badly... :confused:
 
My system doesn't like the C3/C6 being enabled. It locks up randomly. No issue when disabled.
 
Give ThrottleStop a try if you are interested in getting some control over the sleep states while in Windows. It can also accurately report the percent of time the CPU spends in various C States. Not all motherboard bios versions support all features. Turning off some of the C States can make a huge difference in SSD write times.

ThrotttleStop 4.00
http://www.techinferno.com/downloads/

The minimum multiplier in these CPUs can not physically go down to 1 at idle so take that data with a grain of salt and CPU-Z has been designed for validation purposes so sacrifices accuracy for consistency when a CPU is lightly loaded. ThrottleStop tells it like it is using on chip high precision timers and monitoring methods recommended by Intel.

Here is some more info and a screen shot of TS:

http://forum.notebookreview.com/7755405-post728.html
 
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My system will randomly shut down if I have any power saving features in the BIOS enabled. Don't really know why, but I don't plan on keeping this 2500k for a long time anyway.
 
Strange issue when I got home today...

I had been experimenting with different combinations of power saving options in the bios and their effects the night before. Left computer on all night (sleep mode is disabled) and it was fine.

When I left this afternoon I put the computer in sleep mode manually. Came back home later, woke the machine, and it started boot "looping". Would power on, instantly power down, power back up, and then just sit there. No POST, no video. No combination of button pressing would change that.

Finally had to manually reset the CMOS, and gigabytes dual bios saved my ass. The bios was corrupt! A backup was copied, rebooted, and back to factory settings.

I wish I had remembered what combination of settings I had...ugh, I had written every change down since I bought this thing up until last night....

Owell. I'll keep poking.
 
HAH! Unfortunately that doesn't apply to people like myself. I been learnin' how much a hammer hurts by smashing myself in the hand with it since I was 10 :p
 
wabbitseason said:
What do you do if you want your processor to idle at a low frequency but clock up to maximum the instant there's any sort of load and remain there until that load is gone?
Click to expand...

If your looking to save power when idle then probably the simplest way is to enable C3/C6 and disable EIST and C1E. If you want to get to maximum even quicker while sacrificing a little more power then use fixed vcore.
 
Falkentyne said:
ignore what eztune says.

C1E is power saving (Speedstep) handled directly by the CPU itself.
EIST is the same as C1E, except it's handled by the operating system instead of the CPU.
If you enable C1E and set windows 7 to max performance, it will still downclock to 1600 mhz, because the cpu/motherboard is handling the power saving.
If you enable EIST and set windows to max performance, it will act the same as if EIST was disabled (not downclock).
Click to expand...

Summed it terrifically, I learned a lot from your post thanks :)

sig.jpg
 
CPL0 said:
If your looking to save power when idle then probably the simplest way is to enable C3/C6 and disable EIST and C1E. If you want to get to maximum even quicker while sacrificing a little more power then use fixed vcore.
Click to expand...

Thanks, I'll give that a try.
 
except it doesnt work. when i play my games i want my cpu at full multiplier. 4.5ghz in my case. i do not care what the cpu thinks my game needs or doesnt. right now with the games i play it will jump around between 1600, 2500, 3200, and 4500 mhz. no thanks.
 
Forceman said:
It is dynamically changing the clock speed (even faster than CPU-z or whatever is reporting it) to meet the changing load. This is as designed. If you don't want it to do that, but would rather run at 4.5 or whatever all the time, then just disable EIST and C1E.

I find it hard to believe that you are halving your file transfer time based simply in changing your CPU to maximum frequency as that task are not CPU dependent. Can you show some benchmarks for that?
Click to expand...

I know what he's talking about.Basically, a vrey light load might only make the cpu run at 3-4 ghz (if it was set for a maximum of 5 ghz), although a fully loaded single core will be at 5 ghz. I remember that disabling (or enabling?) C3/C6 affected this to some degree, but I don't remember how. There was a way around it, though....
 
when i play my games it does not stay at 4.5ghz 100% of the time if any of the power saving features are enabled. So I leave them all all disabled.
 
LawGiver said:
when i play my games it does not stay at 4.5ghz 100% of the time if any of the power saving features are enabled. So I leave them all all disabled.
Click to expand...

Just because it doesn't stay at 4.5 doesn't mean it "isn't working". It is working as designed, where the CPU speed scales based on the demand. If you don't like that behavior, then it is simple to turn off EIST/C1E, as you have - but that still doesn't mean it isn't working exactly as designed.
 
Working as designed and working appropriately are two completely different things. Why don't you try playing BF3 on a CPU with EIST enabled? There's a very good reason that GPU's don't display this behavior when rendering any remotely demanding game.
 
Looks like certain boards and some SB K editions suffer from multiplier changing during full prime load. I know this doesn't happen on locked SB pinning it to 38 multiplier.
 
wabbitseason said:
Working as designed and working appropriately are two completely different things. Why don't you try playing BF3 on a CPU with EIST enabled? There's a very good reason that GPU's don't display this behavior when rendering any remotely demanding game.
Click to expand...

I do, and mine sits nicely at 4.6 the whole time (I monitor it on a second screen). It might be slowing down in some older, non-demanding games, but if it is downclocking when running BF3 you have different problems than just EIST being on. Have you tried checking your Windows power settings? Did you increase the current load in the BIOS - maybe the CPU is power throttling?
 
LawGiver said:
when i play my games it does not stay at 4.5ghz 100% of the time if any of the power saving features are enabled. So I leave them all all disabled.
Click to expand...

But that is how power saving works. If you do not keep a core busy it will transition to a power saving state. With EIST disabled once it is made busy again it should get back to 4.5GHz fairly quickly and not be noticeable in most situations. What degradation are you seeing in your game and what are you using to measure CPU frequency?
 
As far as I can tell, if you enable C6, then C1E/C3 are enabled regardless of their bios settings.
And if C3 is enabled, then C1E is enabled regardless of its setting.
ie, you can't reach the deeper sleep states without having passed through the upper ones.

I measured on my 4.5ghz 2500k system @ the wall idle (includes ssd, hdd, dvd, 16gb, gtx680)
none : 104W [peak clocks 24/7]
C1E : 90W [downclocks to 1600]
C1E + C3 : 76W [+core gated?]
C1E + C3 + C6 : 62W [+core down?]

There was also that Windows issue which causes some compression tool to run at half speed because it wasn't waking up the cores because the load didn't "look" heavy. I think I'll leave my SB system at full clocks, because it's still 40W less than my previous 920 system at idle! Note that you can never disable the "fine gating" within each core, so max clocks doesn't mean max power. That's a power savings you can't disable.
 
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