i7 4770K C-state issue

[Hail The Brain Slug]

On my shiny brand new 4770K (Which turns out to be the worst overclocking chip ever made, apparently) I can't seem to get c6/c7 working properly. Initially I figured it was because my old power supply (Seasonic M-12 600) wasn't rated to handle the load since it's not on the approved list from Intel.

Well, I jumped on the Seasonic 660 watt platinum power supply deal at Newegg and this power supply is most definitely in Intel's list. But when I enable C6/C7 it still gives me the exact same problem.

Problem: Upon setting package C-state limit to C7 and booting windows, everything is choppy/hanging. The windows loading animation is choppy, the lock screen opening is choppy, and I can't even enter my password correctly because it's choppy and doesn't pick up all of my keystrokes. As soon as I go back into the UEFI and change it back to C3 or auto, everything works fine.

System info:
i7 4770K at 3.9 GHz/1.144 volts
2x4GB G.Skill DDR3 1600
MSI Z87-GD65 Gaming
GTX 260
Seasonic SS-600XP2 (Platinum)

Has anyone else had any experience with C6/C7 and any issues? In the end I suppose it's not such a big deal but if I can take advantage of them I would like to.

 

[TerryMathews]

Do you have the same problems at stock?

 

[Hail The Brain Slug]

Do you have the same problems at stock?

Good question, I suppose this CPU has never truly been at stock since my motherboard is one of them that on "auto" decides the multiplier should be 39 for everything. I'll try booting it with C7 enabled and the proper multipliers for stock settings.

Edit: I changed everything to emulate stock settings for the 4770K and I experienced the same problem. It's even so bad that audio that plays is frozen for seconds at a time (Frozen repeating a very short sound, like when you get a BSOD and audio is playing)

 

[Galatian]

Have you checked your BIOS settings what is in auto? I was reading an article on x-bit labs and they essentially complained, that in most Z87 boards the auto option actually means off and not on.

 

[Termie]

Have you checked your BIOS settings what is in auto? I was reading an article on x-bit labs and they essentially complained, that in most Z87 boards the auto option actually means off and not on.

This is true, but it sounds like the OP has actually manually "enabled" all C-state levels, and that this is causing the problem. The default is indeed "auto", which is often equivalent to "off", but it doesn't seem that's the OP's problem, as he's clearly found a way to adjust the c-state.

I wish I could provide a solution, but this is a very odd problem. I would be curious whether the OP can run CPU-z while in this sluggish c-state mode to determine what the clock rates are, and perhaps flip over to the task manager to access CPU load monitoring.

 

[coffeejunkee]

Very odd indeed. You said C3 worked ok, what if you limit to C6 instead of C7?

Do you have an ssd? There have been reports of c-states hampering ssd performance, but nothing on this scale. Asking anyway.

Almost feels like a defective cpu.

 

[Hail The Brain Slug]

This is true, but it sounds like the OP has actually manually "enabled" all C-state levels, and that this is causing the problem. The default is indeed "auto", which is often equivalent to "off", but it doesn't seem that's the OP's problem, as he's clearly found a way to adjust the c-state.

I wish I could provide a solution, but this is a very odd problem. I would be curious whether the OP can run CPU-z while in this sluggish c-state mode to determine what the clock rates are, and perhaps flip over to the task manager to access CPU load monitoring.

After a little more google research, it might not be worth trying. On auto, my CPU is scaling back to 800 MHz and the voltage drops significantly. The Intel Extreme Tuning Utility reports TDP of 1 watt, CoreTemp reports 0.6 watts. Apparently this sounds about right for C6/C7 states. I just find it strange when I manually set it, I get such an odd problem.

It acts as though it's forced to be in C7 and not allowed to enter a higher power state. Although the setting is named "Package C-State Limit", I think it might not operate as it sounds. I can't find a good description anywhere about what exactly it does.

 

[Termie]

Yeah, I wouldn't worry about it too much. Even if you aren't in C6/C7, you'll only be using about an extra watt, based on my experienced.

 

[TerryMathews]

It acts as though it's forced to be in C7 and not allowed to enter a higher power state. Although the setting is named "Package C-State Limit", I think it might not operate as it sounds. I can't find a good description anywhere about what exactly it does.

The way its so ambiguously written, that may be exactly what its doing (forcing it into the lowest C-state).

There's a program called ThrottleStop that will let you see what C state youre in. Might help to understand what that BIOS setting does.

Is there any reason why you think Auto won't work down into C7 if its appropriate?

 

[Hail The Brain Slug]

The way its so ambiguously written, that may be exactly what its doing (forcing it into the lowest C-state).

There's a program called ThrottleStop that will let you see what C state youre in. Might help to understand what that BIOS setting does.

Is there any reason why you think Auto won't work down into C7 if its appropriate?

Looking in ThrottleStop, it does appear it is appropriately going into C7 at idle. I had searched previously and could not find a program that showed what C state the processor was in, so I was left assuming my old power supply not being certified for Haswell meaning it might not be utilizing it.

Based on what I see now, it looks like my old power supply worked fine allowing my processor to enter C7 also. Good thing I didn't upgrade the power supply for that reason, I just wanted to make sure I was taking advantage of it.

 

[coffeejunkee]

The way its so ambiguously written, that may be exactly what its doing (forcing it into the lowest C-state).

There's a program called ThrottleStop that will let you see what C state youre in. Might help to understand what that BIOS setting does.

Is there any reason why you think Auto won't work down into C7 if its appropriate?

It actually does exactly what it says: limit c-state support. If you set it to C3 it will never go down to C6 or C7.

I ran into this in another thread and was confused at first too. My mobo has separate settings for these c-states.

Looking in ThrottleStop, it does appear it is appropriately going into C7 at idle. I had searched previously and could not find a program that showed what C state the processor was in, so I was left assuming my old power supply not being certified for Haswell meaning it might not be utilizing it.

Based on what I see now, it looks like my old power supply worked fine allowing my processor to enter C7 also. Good thing I didn't upgrade the power supply for that reason, I just wanted to make sure I was taking advantage of it.

Well, it's good to see auto mode is working but it's still strange manually enabling causes problems. Maybe a bios update will take care of it.

As for the psu, the (supposed) problem would be your pc shutting down because when in C7 state voltage would become so low that undervoltage protection would kick in. I suspected as much but it really seems it was all fud.

 

[TerryMathews]

It actually does exactly what it says: limit c-state support. If you set it to C3 it will never go down to C6 or C7.

I ran into this in another thread and was confused at first too. My mobo has separate settings for these c-states.

The behavior of his PC indicates otherwise. Do you have the same motherboard, or is it possible that yours works one way and his another?

 

[coffeejunkee]

No, I have a different mobo (Asus) and like I said I can enable c-states individually. MSI chooses a different way which works just as well, it's just in this case manually enabling causes problems.

The person in the other thread had no problems manually setting it to C7 limit.

 

[unclewebb]

RealTemp T|I Edition
http://forum.techinferno.com/downloads.php?do=cat&id=18
http://www.mediafire.com/download/7h6578x6dh7hc8x/RealTemp_TI.zip

The above version of RealTemp also has Intel C State reporting. Some manufacturers have ambiguous "AUTO" settings in the bios that can change what C States are actually being used. RealTemp T|I will show you exactly what low power C States are being used when your CPU is idle or partially loaded.

When your CPU is being set up correctly by the bios, enabling any of the deeper C States like C6 or C7 should not be causing choppy performance issues. There is either a a problem with the bios or you might have a poorly written driver on your computer.

LatencyMon is a useful tool for tracking down driver issues. Old school drivers can interfere with the C States working correctly.

LatencyMon
http://www.resplendence.com/latencymon

Many users continue to use the Windows Balanced power profile. A modern CPU that has the deeper C States enabled does not save any power by running slowly. A slow CPU is an inefficient CPU and should be avoided. Some smart guys at Berkeley figured this out a long time ago.

Power Optimization – a Reality Check
http://www.cs.berkeley.edu/~krioukov/realityCheck.pdf

 

[Dufus]

It would be interesting if C7 package states were shown to be used. While C7 core state is not significantly different from C6, IIRC a transition to C7 package state should flush L3 cache and this could cause high latency and choppiness if over used. It would be interesting to see if you actually spend time in C7 pkg.