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Disabling Intel C State saved my computer!

C

ChrisN

n00b
Joined
Oct 8, 2009
Messages
27
Specs:
Antec Nine Hundred Two case
MSI P55-GD80 mobo
8 GB Corsair Dominator RAM
ATI Radeon HD 5800
Intel i5-750 CPU
Cooler Master Hyper 212 Plus
Corsair HX750 PSU
Windows 7 64-bit

I feel like I've just had a great weight lifted from my shoulders. I've been locked in mortal combat with my computer for the past couple of weeks. I foolishly flashed my BIOS in an attempt to fix a performance problem I was having (I could only boot into Windows and keep it stable if I set my BIOS settings to fail safe). Well, that started a very long and frustrating series of BSODs (mostly the "uncorrectable hardware" BSOD).

I did a lot of googling on the information I got from Windows Debugger but found all kinds of differing answers (it seems like the default response to any problem is to get new memory!). However, I did repeatedly see some kind of reference to C states. But there was never any real information on what to DO about it.

Finally, after nearly two weeks straight of problems (probably 50+ BSODs) and having to stay in Windows Safe Mode (where it was rock solid), I got fed up and went with the fresh (re-)install of Windows.

However, it hung with a BSOD ("uncorrectable hardware...") near the very beginning ("Expanding Windows files"). It did this twice so I knew it wasn't a fluke.

Thinking that I now had a very expensive paper weight, I decided to go through the BIOS settings one more time. This time I came across a sub-menu I had previously missed and on this menu where two very interesting options: Intel C State and Intel C State Package Limit Setting. Remembering that prior information about C states I quickly googled (on my wife's laptop) these two settings. I found that several people has solved problems with their computers by disabling Intel C State

Figuring I had nothing to lose, I disabled it and rebooted. This time Windows installed without a hitch and my computer has been up and working ever since (well, it's been less than 24 hours but that's still a 'record' in comparison to the past couple of weeks).

I have some questions about this, though.

Was the problem really just a BIOS setting or is there something a little wrong with my CPU?
Will this affect my performance negatively?
Do you think it would be safe to try the "Optimized" BIOS settings instead of the 'Fail Safe'? My concern is the Intel Turbo setting which, I (erroneously?) thought was the trouble a couple of months ago. I put in a lot of time, effort and money to build a pretty strong computer and it galls me that it has to sit there in fail safe mode.

Anyway, any thoughts/comments would be appreciated!
 
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I'm very interested on why the new post Core 2 platforms are having these problems. Either driver issues, user error, or just engineering mishaps.
 
I have had no problems with my i7 X58 or the i5 H55 I put together.

However I don’t touch any of the default bios configurations. I go through and set it up for the hardware I am using and disable any integrated features I won’t be using.

Why the insistence on using default preconfigured setting profiles be they optimized or failsafe?


EngrChris said:
I'm very interested on why the new post Core 2 platforms are having these problems. Either driver issues, user error, or just engineering mishaps.
Click to expand...

Having what problems? If you buy compatible hardware and configure it correctly the platforms have no problems.

User error exists on every platform.
 
Nothing you said is relevant. "Guys, I have no problems with my builds." Congratulations, now how does that address the question? "Compatible hardware" has nothing to do with C-state - at least, nothing you have pointed out.
 
TGA said:
Why the insistence on using default preconfigured setting profiles be they optimized or failsafe?
Click to expand...

I did not see where he was insisting on using default preconfigured setting profiles in his post.
 
TGA said:
However I don’t touch any of the default bios configurations. I go through and set it up for the hardware I am using and disable any integrated features I won’t be using.

Why the insistence on using default preconfigured setting profiles be they optimized or failsafe?
Click to expand...

These two statements confused me.

If you don't touch any of the default configurations, how do you "go through and...disable any integrated features I won't be using"? How can you keep your hands off and then also 'tinker' with the BIOS?

Or are you saying that you don't USE the default BIOS configurations?

If so, you may have noted that I'm NOT using the default BIOS config - I've disabled C state.

But, more to the point, IMHO, one shouldn't HAVE to 'tinker' with the BIOS in order to get it running.

To fine tune it or over clock it, sure. But not just to have it run.

My hardware matches my Motherboard, so I shouldn't have to make any changes if I simply want my machine to run.

So, is the Intel C State option an "unnecessary" option?
Is there a bug in the BIOS?
A bug/manufacturing error in the Motherboard?
A bug/manufacturing error in the CPU?
Should I enable Intel C State and then 'tinker' with Package Limit settings?
Should I go ahead and turn Turbo on or should I just keep things as is?
 
Really cause after everything he said he basically ended it with saying “Do you think it would be safe to try the "Optimized" BIOS settings instead of the 'Fail Safe'?”

Optimized over failsafe profile may reduce the number of things you need to configure manually but beyond that these profiles are useless.

And yes OP by disabling C states you’re no longer running a default profile. However c states being enabled should in no way force you to run in safe mode to have a stable OS. It should be clear that the default profile is not getting the settings right for your hardware.

So if it wasn’t clear by my first reply I will come out and say it. No you should not load optimized defaults you should go through and set the settings to match the hardware you bought rather than hoping a default profile gets your ram timings right for example. As this is where you problem likely exists.

You could be like those posts your were reading and replace your ram until you get a set that agrees with the settings your letting the bios decide or you could configure the bios to match the timings of the hardware you already have.
 
I hear you, TGA, but you're not really answering any of my questions/concerns.

Do you have any insight into C states and why I would have a problem with it being enabled?
Do you think it's a bug/manufacturing error in the BIOS, MB and/or CPU?
Do you have any information about what I'm missing/losing by having C States disabled?
Do you have any knowledge about the Package Limit Settings? Will a different setting there (default = Auto) overcome the problem I'm having and allow me to enable C State?
Do you have any insight into Turbo mode and whether I should enable it?

And if your answer is something along the line of "just keep trying them until it's stable" then please don't bother to respond because you're neither helping nor adding anything to this discussion.
 
Here's how these new CPUs work. The amount of turbo boost a Core i CPU gets is based on how many cores are active and how many cores are inactive in the C3/C6 sleep state. A Core i5-750 has a default multiplier of 20. With C States enabled, this CPU can use full turbo boost so a single core can use a multiplier as high as 24 when the other 3 cores are in the C3/C6 sleep state. These CPUs are constantly transitioning a hundred times a second so the maximum multiplier can be changing back and forth, usually between 21 and 24.

With C States disabled then the maximum multiplier will only be 21 regardless of how many cores are in the active state. It's a lot easier keeping that stable than trying to keep a multiplier that is randomly hitting 24 stable.

Here's a good tool so you can watch what your multipliers are really up to on each thread. With C States enabled, run a single thread of Prime95 Small FFTs and you can watch a single core use a higher multiplier as the others ones take naps. If you go into the Task Manger and lock Prime95 to a single thread so it is not moving around then it should become even more obvious how these CPUs work.

i7 Turbo
http://www.fileden.com/files/2008/3/3/1794507/Turbo.zip

ThrottleStop is another good program to keep an eye on these new CPUs.
http://www.fileden.com/files/2008/3/3/1794507/ThrottleStop.zip

By using high performance monitoring timers within the Intel CPU, you get a much more accurate look at things compared to some popular monitoring programs that round the data off to the nearest whole number.
 
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The C states (just C3/C6/C7) caused problems with USB audio, and I was so pissed when I started being productive with my new rig. It also wrecked havoc on my PSU since it would squeal all over the place due to all the power savings. So, the PSU that I RMA'd probably was never defective in the first place. And I was so sure that I got away from the CPU whine present in C2D laptops...
 
This problem could just be the motherboard setting the CPU voltage too low by default or the RAM getting the wrong default SPD timings set by the motherboard, including voltage. If the CPU no longer crashes when it's not "turboing" the first thing I'd look at is CPU voltage.
 
Astral Abyss said:
If the CPU no longer crashes when it's not "turboing" the first thing I'd look at is CPU voltage.
Click to expand...

I agree. Once correctly set up, turbo boost is a great performance feature. If it doesn't crash with this feature off and it does crash with this feature on then a little extra CPU core voltage can solve the problem. I'm not a big fan of the AUTO setting in the bios for critical items like CPU voltage.

Whenever you put together a new computer you need to do some basic stress testing. A computer that has constant random BSOD issues is very unlikely to be Prime95 or LinX stable for any length of time.

Maybe instead of the title, "Disabling Intel C State saved my computer!", that should be changed to, "Disabling Intel C State slowed down my computer!" and made it more stable since it was not correctly setup in the first place.
 
Here are my current voltage settings:

In my BIOS there is a setting called "Set VDroop" that has 2 options - High and Low. When set at High (which is the default), the BIOS follows Intel specs (so it says) in setting voltage.

Vcore - 1.00625
VTT 1.126
PLL 1.8
DRAM 1.53

CPU base frequency 133
CPU ration 20

I'm still looking for what Intel says should be the base Vcore setting.
 
http://aphnetworks.com/reviews/intel_core_i5_750

I did a quick Google and found this screen shot. I think your CPU needs some more juice and maybe your memory too. It's better to start with a little too much and work your way down rather than not have enough and lose stability and lose performance because you have to disable most of your turbo boost.

Do some more searching and see what other users are using for this CPU.

1.168 volts in CPU-Z seems like a good place to start. If you are stable running benchmarks then you can go lower and test again.
 
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ChrisN said:
Here are my current voltage settings:

In my BIOS there is a setting called "Set VDroop" that has 2 options - High and Low. When set at High (which is the default), the BIOS follows Intel specs (so it says) in setting voltage.

Vcore - 1.00625
VTT 1.126
PLL 1.8
DRAM 1.53

CPU base frequency 133
CPU ration 20

I'm still looking for what Intel says should be the base Vcore setting.
Click to expand...

The Vcore setting varies by processor (Intel has a wide range in their spec and it just depends on what the processor is rated at when Intel tests them) so it's hard to say if that's low or not. Try setting the Vore to 1.30v (still well within Intel spec for the chip) and see if you can turn C state back on. If you can, you found the problem. If you still can't, the problem lies elsewhere.
 
Thanks Unclewebb & Astral Abyss.

I've changed the VCore and DRAM settings.

VCore is now set at 1.168 and DRAM at 1.65 (which is what Corsair recommends)

Right now I'm ensuring that the system (with C state disable) is stable (it seems to be, but after fighting with this for two weeks straight, I don't take anything for granted).

If it remains stable, I'll enable C state and see how it goes.

In the meantime, I left VTT and PLL settings alone. Should I leave them that way?

Also, my board as OC Genie. I haven't played around with it because until now I haven't even been able to get the system stable when it ISN'T being overclocked.

What are your thoughts about me using the OC Genie. Would overclocking the system a bit actually help my problem with the C state?
 
I think setting the Vcore to be constant (not fluctuating) does help quite a bit. At least it did with me. USB audio doesn't cut out as much, but the problem was still present. I think I'll play around a bit more...

As for overclocking, I wouldn't do it with Turbo mode on. Vtt should not go over 1.21V. Overclock if you have 1600MHz RAM.
 
ChrisN said:
Thanks Unclewebb & Astral Abyss.

I've changed the VCore and DRAM settings.

VCore is now set at 1.168 and DRAM at 1.65 (which is what Corsair recommends)

Right now I'm ensuring that the system (with C state disable) is stable (it seems to be, but after fighting with this for two weeks straight, I don't take anything for granted).

If it remains stable, I'll enable C state and see how it goes.

In the meantime, I left VTT and PLL settings alone. Should I leave them that way?

Also, my board as OC Genie. I haven't played around with it because until now I haven't even been able to get the system stable when it ISN'T being overclocked.

What are your thoughts about me using the OC Genie. Would overclocking the system a bit actually help my problem with the C state?
Click to expand...

I'd leave them alone. You shouldn't need to really mess with those unless you're doing massive overclocking, and even then it doesn't always do much.

Keep in mind that 1.168v may or may not be enough volts for your particular cpu. If you get a blue screen, don't be discouraged, just try a little more voltage.

I'm not a big fan of OC genie because it's going to automatically increase your voltages by whatever amount it feels like as you increase your bus frequency. I prefer to do that myself. It's your call.
 
OK, I upped the Vcore to 1.2 (just to be sure - and it's still WELL within tolerance) and then enabled C states.

It's been about 5 minutes and no BSODs, but it will take longer than that to ensure it's stable.

Now, if this works (and even if I have to bump the Vcore up a bit more), should I enable Turbo Mode?

Or should I just try to Overclock it a bit?

I picked the parts of my computer carefully and they are all advertised as being easily OverClocked.

I'm not looking for huge performance increases, but a little extra "muscle under the hood" would be nice.

Thoughts/suggestions?

EDIT/UPDATE:
Three hours and still going strong!
 
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Over 24 hours later and still running well!

Thank you one and all for helping me out.
 
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