Voltage discrepancy

Stiffex

Stiffex

Stiffex

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Cheshire
Ive overclocked my system and left the core volts on auto and when i run CPUz it is showing core voltage as 1.344 but when i check in the Bios my V Core is 1.187 so why is there this huge difference ? Is my bios correct or is CPUz ?

My CPU is i7 860 & my board is Gygabite p55 ud4 and i have disabled LLC which knocked o.016 off cpuz reading which was 1.360

Any suggestions would be welcome
 
Don't overclock with the cpu voltage set to auto. Any guide I've ever seen about overclocking is very clear on this point.

Cpu-z is more likely to be accurate, though a multimeter beats either. Set the voltage manually in the bios (probably to 1.375 or so) then decrease it as far as you possibly can before you lose stability.

What speed are you running at?
 
OK my stock speed was 2.8ghz and my overclock speed thus far is 3.68ghz.

What i did was to keep LLC disabled and set the v core to manual @ the reading that was in my bios 1.187v and i got a blue screen just before the desktop so then i kept LLC disabled and set the v core to 1.212v and i managed to boot with no issues so far, although i havent stressed it yet.
However: my CPUz core reading is showing 1.168v and im a bit confused. A guy on youtube says Gigabyte boards have a tendency to overvolt but this is quite a bit lower than what i set it at which is the inverse of what i set it at before and that was quite a bit higher, no wonder im confused.
 
LLC is the same as vdroop no?

So, instead of seeing a vcore drop when under load with vdroop (or LLC) enabled, turning it off results in a lower vcore @ idle, and a vcore increase under load.

Is that correct? I tend to leave vdroop on.
 
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Nope. load line calibration is a mechanism which attempts to keep load and idle voltages the same. Under load the voltage across the processor drops, llc ramps the supply voltage up to compensate. I don't think this is a very good idea, but the majority of people seem quite fond if it.

Vdroop is the voltage decreasing from idle to load. So llc is a means of defeating vdroop. Evga boards (possibly others) refer to it as "vdroop off", so llc=vdroop off but llc ~=vdroop.

The end result is llc on lets you set a lower voltage in the bios, and see a lower voltage when idle. llc off means you set a higher voltage in the bios, see the same load voltage as before, and lose sleep worrying about fourier methods and just how high the transient voltage spikes are.

I wonder if usb oscilloscopes exist
 
JonJ678 said:
Nope. load line calibration is a mechanism which attempts to keep load and idle voltages the same. Under load the voltage across the processor drops, llc ramps the supply voltage up to compensate. I don't think this is a very good idea, but the majority of people seem quite fond if it.

Vdroop is the voltage decreasing from idle to load. So llc is a means of defeating vdroop. Evga boards (possibly others) refer to it as "vdroop off", so llc=vdroop off but llc ~=vdroop.

The end result is llc on lets you set a lower voltage in the bios, and see a lower voltage when idle. llc off means you set a higher voltage in the bios, see the same load voltage as before, and lose sleep worrying about fourier methods and just how high the transient voltage spikes are.

I wonder if usb oscilloscopes exist
Click to expand...

Oh, ok. I get it now.
 
JonJ678 said:
Nope. load line calibration is a mechanism which attempts to keep load and idle voltages the same. Under load the voltage across the processor drops, llc ramps the supply voltage up to compensate. I don't think this is a very good idea, but the majority of people seem quite fond if it.

Vdroop is the voltage decreasing from idle to load. So llc is a means of defeating vdroop. Evga boards (possibly others) refer to it as "vdroop off", so llc=vdroop off but llc ~=vdroop.

The end result is llc on lets you set a lower voltage in the bios, and see a lower voltage when idle. llc off means you set a higher voltage in the bios, see the same load voltage as before, and lose sleep worrying about fourier methods and just how high the transient voltage spikes are.

I wonder if usb oscilloscopes exist
Click to expand...

That doesnt explain why im now reading lower in CPUz than the manual voltage ! When i was on auto Bios=1.187 CPUz=1.360
Still on auto - LLC CPUz=1.344
went on manual and Bios=1.212 CPUz=1.168
So why is my slight increase in bios voltage result in an even lower CPUz reading ?
Dont forget, a lower bios voltage resulted in a massive 1.344 CPUz reading.
jsc1kQtF.png


I have stressed this with Orthos for 1 1/2hrs and burnt a number of data discs at the same time and not a peep of instability.
 
Hello Stiffex,

welcome to OcUK Forums! :)

Stiffex said:
when i run CPUz it is showing core voltage as 1.344 but when i check in the Bios my V Core is 1.187 so why is there this huge difference ?
Click to expand...
Hmmm, I wonder, is that reading in CPU-z (Windows) when the processor is idle or loaded? . . . . I'm thinking that maybe its loaded and the reading in BIOS is semi idle? :confused:

JonJ678 said:
Don't overclock with the cpu voltage set to auto. Any guide I've ever seen about overclocking is very clear on this point.
Click to expand...
Heh stop reading guides Jon and do some testing for yourself! :p

While [Auto] vCore may not always be the best way there is certainly no harm in using it, especially if one is new! ;)
 
Big.Wayne said:
Hello Stiffex,

welcome to OcUK Forums! :)

Hmmm, I wonder, is that reading in CPU-z (Windows) when the processor is idle or loaded? . . . . I'm thinking that maybe its loaded and the reading in BIOS is semi idle? :confused:

Heh stop reading guides Jon and do some testing for yourself! :p

While [Auto] vCore may not always be the best way there is certainly no harm in using it, especially if one is new! ;)
Click to expand...

I havent had much load on the CPU Big Wayne, i check the settings in CPUz before i do any stressing but that high v core was on auto which has a tendency to over volt, now im purely manual and we have the complete reverse of the situation.

My v core in the bios is set to 1.237 and here is my stressed reading :

r9siWEsd.png


Make of it what you will :confused:
 
That looks normal in the screenshot above! :)

That is either vDroop or vDrop, does that vCore figure increase or decrease according to load? i.e when you turn off Prime does tha vCore rise up again?
 
ok its the same reading in the bios and cpuz now that im doing it manually but still lower than what im setting the v core at so i think your right Big Wayne i have a touch of v droop.

I took the bclk up a touch to get over the 3.8ghz mark had to take the voltage up a touch and i hit instability and now it fails prime 95 @ the settings i had it at before. Would you suggest clearing the cmos and starting again ?
 
If the voltage sags once the system is loaded that vDroop!

If the voltage is just always lower than what you set in the BIOS regardless of idle/load that's vDrop . . .the latter is 99% the norm and nearly always causes confusion to the laymen overclocker! :p

Regarding your clock I would say it better to get a good solid base and work your way upwards, slowly but surely. Some people prefere to just go bish bash bosh and scramble at ful speed upwards heading for 4GHz but that method has never worked for me personally . . . ymmv ;)

Btw is that a single thread prime you are running there? . . . maybe it would be better if you downloaded and ran the latest version for giving your kit a good multi-threaded kicking! :D
 
Do you know if vdrop is a calibration issue or a result of the processor never being measured when truly idle? I suspect the latter, though I don't know.
 
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