Intel i7 - Turbo + C-State = Fail

[WeeMaan]

Hello!
I have a disturbing problem, I now have a rock stable clock on 4,2ghz (21*200) @ 1,36v HT on.
But if I turn C1E or C-State on then I get BSOD on boot, or within minutes after entering the OS (win7 64).

The system is as follows:
P6T Deluxe v2 with 0006 bios (same with 0406, 0504 etc).
i7 920 D0 (cooled by a thermochill 120.4, ddc 3.2 etc)
Corsair Dominator 1600mhz 8-8-8-24

Anyone know if there are any solutions?
Perhaps someone else had this problem and fixed it somehow?

[Chri$ch]

If you enable C-State in Bios then worked the higher turbo multiplier on one core (22*200), so that can be the problem

[Hornet331]

The solution is to disable C1E

C1E reduces the voltage when the CPU idels, and if it doesn't switch fast enough when theres load again on the cpu there to less voltage for the desierd speed and you get a BSOD.

On gigabyte boards, C1E is disabled when you set manual votlages (even with the C1E option is enabled in the options menu).

[WeeMaan]

If you enable C-State in Bios then worked the higher turbo multiplier on one core (22*200), so that can be the problem

Okay, but are there any way of having C-State enabled but not the 22x multi?

The solution is to disable C1E

C1E reduces the voltage when the CPU idels, and if it doesn't switch fast enough when theres load again on the cpu there to less voltage for the desierd speed and you get a BSOD.

On gigabyte boards, C1E is disabled when you set manual votlages (even with the C1E option is enabled in the options menu).

You know if it's the same on Asus boards?
If it is then C1E does'nt matter, so we narrowed it down to C-State only.

Correct me if I'm wrong but does'nt C-State shut down parts of the cpu when they are not being used?
Does it do anything more than that?

[Hornet331]

Okay, but are there any way of having C-State enabled but not the 22x multi?

Disable turbo and multi 22 is gone (but also 21).
If you enable the c-states, by which i think you mean the higher states like C3,C6,C7, theres no way you can prohibit the cpu to go into multi 22x when turbo is enabled.

Its managed by the PCU in nehalem.

Also there are many different C-stats .

[WeeMaan]

Disable turbo and multi 22 is gone (but also 21).
If you enable the c-states, by which i think you mean the higher states like C3,C6,C7, theres no way you can prohibit the cpu to go into multi 22x when turbo is enabled.

Its managed by the PCU in nehalem.

Also there are many different C-stats .

Yeah, that makes sense. Because when I have turbo off then C-state or C1E works.
But i guess I will just have to have C-State and C1E disabled then.

Thanks for your answers.

[donmarkoni]

Does anyone get lower memory bandwidth when disabling C-states?

[bentez2003]

Yes I do!

at 4Ghz c-state tech enabled i get 20k / 18.25k / 22k read/write/copy in everest 5.02175

at 4.2ghz c-state tech disabled i get 17.5k /14.5k / 19.5k

what would cause this and how can i fix it?

Thanks

[donmarkoni]

Yes I do!

at 4Ghz c-state tech enabled i get 20k / 18.25k / 22k read/write/copy in everest 5.02175

at 4.2ghz c-state tech disabled i get 17.5k /14.5k / 19.5k

what would cause this and how can i fix it?

Thanks

Sorry for not posting here an update. It follows... (from i4memory http://i4memory.com/f80/cxe-stabilit...tml#post119398)

Well, after many hours of testing and loosing nerves, I came to a conclusion that I made one crucial mistake:
Using just one application to test memory bandwidth - Everest 5.02
I like it very much and been using it for years every day, so I trusted it.
Obviously Everest has issues with some pieces/combinations of HW and/or BIOS settings.
There is NO CHANGE IN MEMORY BANDWIDTH with CxE Disabled/Enabled according to Sandra 2009.5.15.99 and MemTest 2.11 and Stream 5.8 memory bandwidth test prog http://www.cs.virginia.edu/stream/
Also Crysis benchmark shows no impact in FPS when CxE disabled.
It would be a good thing if someone can confirm these findings.

So, if you could try and confirm (or deny) my findings it would be great.
I was using Everest 5.02.1750 as you are. Tried all up to .1850 (using now) and all is the same.

BTW, look at my BIOS settings (http://i4memory.com/f80/cxe-stabilit...66/#post119232) if you like, you might find something usefull. Or not.
You will notice that I'm using AUTO for CPU VID and percentage increase for it, so I have CPU running @ 2.4GHz 1.232V idle and 4.2GHz 1.424V full load (20W idle, 150W load).

[bentez2003]

Donmarkoni thanks alot for your reply, i will try out sandra when i get home and report back, thanks again!