Please help! - Bios cpu voltage vs CPUZ core voltage??

[johnsmith221]

Currently i'm at 4.0ghz stable... But-

i noticed that CPUZ consistantly reads my core voltage 0.2v higher than what my bios reads it. (i.e. 1.2v in bios shows up as 1.4v in CPUZ)
Everything i have found online is for the opposite case where cpuz is lower voltage and is explained by "vdroop" or "vdrop" but somehow i am different?

Please help me to understand what is happening. is Bios correct or is CPUz correct?

If bios is correct i can do 4.5ghz @ 1.25v but in cpuz this appears as 1.45v which scares me.... also everytime i change the offset even by smallest increment (-.005 i have had bsod on startup or in intelburn)


Results:


4.6 (Auto) Bios 1.3v / CPUZ 1.5v - seems stable but cpuz# is scary
4.6 (-.005) Bios 1.1v / BSOD on startup

4.5 (Auto) Bios 1.25v / CPUZ 1.45v - seems stable but cpuz# is scary
4.5 (-.005) Bios 1.1v / CPUZ 1.32v BSOD on intel burn

4.4 (Auto) Bios 1.2v / CPUZ 1.4v - seems stable but cpuz# is scary
4.4 (-.005) Bios 1.1v / CPUZ 1.32v BSOD on intel burn

4.2 (Auto) Bios 1.18v / CPUZ 1.38v - seems stable but cpuz# is scary

4.0 (Auto) Bios 1.1v / CPUZ 1.30v - current



My Build:

Asus p8z68lx
i5 2500k
hyper 212+ (so far max heat any time has been 67C so heat is not limiting factor)

 

[madchemist83]

Yeah lx board is very limited about voltage control. I'm pretty sure cpuz is the real voltage. So u don't want it to be more then 1.4 also temps of 67 are kinda high.

 

[Deleted member 217926]

67C is great but 1.4v is over where you want to be. To make the chip last you really want under 1.36v. Looks like you might be stuck at 4Ghz with that motherboard.

 

[vollman1]

Check this guide and terminology out. Its written for a p67 mobo, but should work with a z68 mobo.

http://www.clunk.org.uk/forums/overclocking/39184-p67-sandy-bridge-overclocking-guide-beginners.html

 

[Deleted member 217926]

Check this guide and terminology out. Its written for a p67 mobo, but should work with a z68 mobo.

http://www.clunk.org.uk/forums/overclocking/39184-p67-sandy-bridge-overclocking-guide-beginners.html

It's his motherboard's lack of voltage control that is the problem. And he knows it.

 

[johnsmith221]

One more related question-

I start CPUZ as soon as windows starts and notice it shows a high voltage number. When i start IBT and under 100% load this voltage number dropsi havent paid much attention but i dont think it ever climbs all the way back up to where it started even after ibt or idle or regular use... is that normal?

 

[vollman1]

yeah it's normal. You can adjust this in your bios. Basically, when your system is running at 100% the PSU is pumping power out to all components and the voltage to the cpu slightly drops.

Edit: check out that guide that I linked above it covers some general OCing topics.

 

[madchemist83]

No it's called vdroop. It's controled by llc level which u can't change on ur mobo. Has nothing to do with psu

 

[vollman1]

Yes it is called vdroop. Power passing through the MOSFETS causes the voltage to go lower.

Anyway, the LX should have LLC setting, no? I have the p8z68-v Gen3 and I am pretty sure they have the same option in the bios.

Edit:

The guide covers this.

 

[madchemist83]

No. all it is is auto, on and off

 

[vollman1]

Auto, on and off?! That sucks.

 

[madchemist83]

I know. That's why I love my deluxe gen3

 

[johnsmith221]

No it's called vdroop. It's controled by llc level which u can't change on ur mobo. Has nothing to do with psu

ok, but that makes me curious. Should you use this initial startup voltage as a guide for your core voltage? or do you go by voltage at 100% load?

i think the 100% load reading is the realistic number but could that spike on startup fry your cpu if not accounted for?

 

[madchemist83]

Yes that's why u go with offset. Set ur multi to 45 and look in real temp for vid and for ur vcore then vid minus vcore gives u offset. Set it at that value or lower.