Vcore Stability and drop?

S

Scouras626

Weaksauce
Joined
Jul 2, 2003
Messages
65
Hi everyone.
I just built a new machine to replace my old P4 northwood.
It's an Asus p5k Deluxe with a E6420 C2D, and the DDR2-1066 Ballistix.

I've been realizing that the voltage actually going to the processor is significantly different than what i set it at in the BIOS. (at least that is what the software says)
Like I can set it to 1.45v and it will be reported around 1.41v.
This drop seems to be present regardless of the initial voltage, 1.3875 in BIOS can be reported around 1.34.

I'm also getting fluctuation in the voltage, particularly when stress testing the proc. It can lower another .01v or .02v and fluctuate back up and down from there.

Are the initial voltages likely to be accurate, regardless of what is set in BIOS?
Is this fluctuating normal/safe?

The PSU is a Corsair 620HX.

Temps on the proc are good. OCing 400FSB * 7 for a 2800MHz clock, and running the ram at DDR2-800.
Idles at 25/26 and loads around 42.

RAM voltages are rock solid btw., and the 3.3, 5, and 12V lines look pretty good according to Asus PC Probe II.

Thanks for the info!
 
OMG .04V is gone ! call the voltage police ! :p

Its designed in by Intel to work that way, the voltage regulation circuirty cannot instantly respond to spikes and transients created by quick changes in the current needed by the processor. Think about it, hitting start on Orthos can in a millisecond raise the current draw of the processor from 1A to 16A. Very expensive to design a circuit that can cope with that and keep the voltage from changing.

More than you want to know is found here:
http://www.thetechrepository.com/showthread.php?t=126

There are mods and people do some strange things to their boards becasue they get all bent out of shape over Vdroop, whatever, its your stuff and do what you want. Intel designed it in for a good reason and I dont pretend to know more about Intel CPUs and proper power delivery than Intel.

Entire Intel design guide for cpu voltage regulators, you will find a section specifing the required Vdroop.

http://www.intel.com/design/processor/applnots/313214.htm
 
Awesome, thanks a lot. :)

No Vdroop mods for me :p

So when people say they run their proc at a certain voltage (for OC specs or whatnot) do they typically give the BIOS Vcore or the typical voltage that is reported in monitoring software?
 
The Vdroop seems to be more pronounced on Asus boards for some reason. Not sure why that is.

Not sure what most people give as their voltage when they say they OC. I usually give the voltage I set in bios with a note saying what it is reading in Windows. My T-force 550 board at work actually gives more voltage than what I set it to in bios (1.375V in bios...1.41V in Windows).
 
I (and I think most others, but I hate to talk for anyone else) give the bios setting, the actual voltage is less as you have noticed. Also usually only the montitor software supplied with the board is anywhere near accurate, most others read the Vid which is a register on the CPU as to what the cpu is requesting for voltage, this is ignored when you manually set it in the bios.
 
Scouras626 said:
Hi everyone.
I just built a new machine to replace my old P4 northwood.
It's an Asus p5k Deluxe with a E6420 C2D, and the DDR2-1066 Ballistix.

I've been realizing that the voltage actually going to the processor is significantly different than what i set it at in the BIOS. (at least that is what the software says)
Like I can set it to 1.45v and it will be reported around 1.41v.
This drop seems to be present regardless of the initial voltage, 1.3875 in BIOS can be reported around 1.34.

I'm also getting fluctuation in the voltage, particularly when stress testing the proc. It can lower another .01v or .02v and fluctuate back up and down from there.

Are the initial voltages likely to be accurate, regardless of what is set in BIOS?
Is this fluctuating normal/safe?

The PSU is a Corsair 620HX.

Temps on the proc are good. OCing 400FSB * 7 for a 2800MHz clock, and running the ram at DDR2-800.
Idles at 25/26 and loads around 42.

RAM voltages are rock solid btw., and the 3.3, 5, and 12V lines look pretty good according to Asus PC Probe II.

Thanks for the info!
Click to expand...

That is called Asus ingenuity. We don't call Asus the king of Vdroop for nothing.
 
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