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Question: VCORE higher than what I'm setting it..

Last response: in Overclocking
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October 14, 2010 5:01:21 PM

Okay, to start..

X3 740 BE
ASROCK 870 Extreme3
GSKILL 4GB 1600 CL7
CORSAIR TX850
EVGA GTX 460


So anyway.. I noticed while overclocking, that my vcore is always higher than what I set it -- especially under load. It jumps anywhere from .25 - 1v. This occurs even at default BIOS settings. LLC is disabled.

Running Prime95 now, for example, and my VCORE is listed in several apps fluctuating 1.46-1.50. It's set in the BIOS at 1.4.

So my question is whether or not this is normal behavior -- if not, should I RMA the board?
October 14, 2010 7:43:31 PM

try disabling Vdroop if you have the option and see if that fixes it.
October 14, 2010 8:16:45 PM

No setting like that. :( 
Related resources
October 14, 2010 8:37:48 PM

I forgot to say that it also displays higher in the BIOS, not just CPUID/HWmonitor/etc. It was set to 1.4, displaying 1.464 in BIOS. Now set at 1.35, displaying 1.38+.
a c 197 K Overclocking
October 14, 2010 8:55:20 PM

I don't think you have anything to worry about. The board is consistently reporting the voltage .03 to .06 volt higher than the setting. What happens when you change the voltage is that you dump some bits into a D/A converter that programs the motherboard CPU power regulator to produce that voltage.

The only time that error will have any consequences is at the top end of the permissible CPU voltage range. And you should be using the voltage reading, not the BIOS setting, anyway.

One of my Intel Gigabyte motherboards produces a voltage very close to the BIOS setting. Another one produces a voltage about .05 volt low.

I monitor the CPU voltage in the PC health section of the BIOS and with CPU-Z.

Oh, and vdroop is not a BIOS setting. It's an integral part of the power regulator deliberately designed into the regulator.
October 14, 2010 9:03:59 PM

Oh, and vdroop is not a BIOS setting. It's an integral part of the power regulator deliberately designed into the regulator.

-- That's what I thought

I monitor the CPU voltage in the PC health section of the BIOS and with CPU-Z.

-- I was looking on CPUZ and in the H/W monitor area of my BIOS, and yeah it reports higher than what I set it at.. it increases further with load. I did notice that it absolutely refuses to go over 1.55v in its random increases, which the BIOS has listed as the upper limit for my CPU. So, if I set to 1.475, it jumps but refuses to go over 1.55v.

Not really sure what to make of it. So you think I'm okay?
a c 197 K Overclocking
October 15, 2010 1:00:12 PM

I think so. Others may argue, though. :) 

All it takes is a very small offset in the D/A converter that controls the motherboard power regulator. If the offset is negative, it yields a voltage lower than the BIOS setting. When that happens, everyone says, <shrug>"no big deal. It must be vdroop." And they just march on.

On the other hand, if the offset is positive and the power regulator produces a voltage a little larger than the BIOS setting, the reaction is different. It's, ":o  What's wrong."

Now, it's possible that you could have a stuck bit. About the only way that you could determine that is to start off at the lowest voltage your CPU will run (maybe underclock it), boot, measure the voltage, reboot and increase the voltage by one step. And repeat up until you reach the highest voltage that you are comfortable with. The problem that you will run into is that the voltage steps in BIOS will be finer than the A/D converter monitoring the voltage can read.
October 15, 2010 2:38:40 PM

I can enable or disable Vdroop in my bios. I'm not saying it's an option on all boards but it is on mine, and with it enabled it jacks up my Vcore about .03 higher under load than what I set it at. With it turned off it is pretty close to what I set it at, less that .01 different.

EDIT: I checked and it is actually called Vdrop in my bios, I've always assumed it was the same thing.

http://www.xbitlabs.com/articles/mainboards/display/asr...
a c 197 K Overclocking
October 15, 2010 5:56:22 PM

I checked a few sites and I do not think it is the same thing.

It looks like the "vdrop" feature is designed to compensate for, not eliminate, vdroop.

From http://www.thetechrepository.com/showthread.php?t=126

"VCC (Vcore) and Vdroop Explained

Load line droop (or Vdroop) is an inherent part of any Intel power delivery design. A current proportional to the average current of all active channels flows through load line regulation resistor RFB. The resulting voltage drop across RFB is proportional to the output current, effectively creating an output voltage droop with a steady-state value. Equation 2 dictates the value for RFB that should be choosen to satisfy the Intel VRD specification (the source of RLL) based on a) the number of power delivery phases (N) and b) the equivalent series resistance (ESR) of the inductor used, effectively known as DCR.

The first question that may come to mind is why droop voltage at all. Truthfully, in most cases the designer may determine that a more cost-effective solution can be achieved by adding droop. Droop can help to reduce the output-voltage spike that results from fast load/current demand changes. The magnitude of the spike is proportional to the magnitude of the load swing and the ESR/ESL of the output capacitor(s) selected. By positioning the no-load voltage (VNL) level near the upper specification limit (bound by the Vccmin load line), a larger negative spike can be sustained without crossing the lower limit. By adding a well controlled output impedance (RLL), the output voltage under load can be effectively 'level shifted' down so that a larger positive spike can be sustained without crossing the upper specification limit (such as when the system suddenly leaves a heavy load condition). This makes sense as the heavier the CPU loading the smaller the potential negative spike and vice versa for lower CPU loading/positive spikes. The resulting system is one in which the system operation point is bound by Vccmin and Vccmax at all times (although short excursions above Vccmax are allowed by design)."
October 15, 2010 6:56:41 PM

What version of the BIOS do you have?
October 15, 2010 6:59:32 PM

That would explain why my voltage goes up instead of down under load with it enabled. Sorry about hijacking your thread raptureseven.
October 15, 2010 7:21:10 PM

haha it's no problem, and I have 1.60 which is apparently the latest version

afaik drop and droop are two different things, I ran into them while researching my issue(?)

idk what's up
October 15, 2010 7:32:49 PM

I wouldn't worry about it, that's fairly common and from what I've seen looking into the same thing for my board it happens alot with asrock boards. just go by what CPU-Z reports and adjust the bios accordingly.
!