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Varying voltage readings

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July 24, 2011 6:30:10 PM

Hey,

I was studying my voltages for a while and this bought up a number of questions in my head, I think I know the answers but wasn't too sure. So...

The voltage I set for my Vcore seems to have three differing values. The first is what I have set in the BIOS, the second is what HW monitor, or CPUID reports to me when the CPU is idle and the third is what is reported by these programs when the CPU is under load. Am I right in thinking the following:

1) The first value is simply what I set in the BIOS
2) The second value is the actual voltage of the CPU after the Voltage offset has been taken into account. The Voltage Offset being the difference between the value you set in the BIOS and the actual voltage value.
3) The third value is the actual voltage of the CPU under load after Voltage Droop. Voltage Droop being the process of reducing the voltage for the CPU to keep heat more under control.

So, if this is correct, which values should I be going on? For example, if my CPU was stable at, say 1.3v. Should this be what I set in the BIOS, or should I be setting the voltage higher in the BIOS so that the actual voltage (i.e voltage 2 from above) is 1.3v?

Also, is this applicable for all voltages. I notices my VDIMM also had differing values in the BIOS and in CPUID.

Thanks in advance.
a b à CPUs
a b K Overclocking
July 24, 2011 7:21:03 PM

I go by the software...I set my voltages in BIOS and CPUID usually tacks on another 25mV...I used to experience vdroop under load...This new board actually raises the voltage during loading by 25mV...So I have to compensate for this in my BIOS: Example BIOS vcore: 1.500v--CPUID voltage @ idle 1.524v--CPUID voltage under 100%load 1.548v
a b à CPUs
a b K Overclocking
July 25, 2011 12:30:05 AM

The voltage you are seeing during idle is the CPU putting itself into low-power idle mode and reducing speed and voltage. It does this to save on wear and tear, plus to save you money on your electric bill. You can turn the low-power idle mode off, but it requires disabling several BIOS settings.

The voltage at load should be very near the value you set in the BIOS. It might not be exact though, depending on other BIOS settings.

You should always set the BIOS voltage to what your CPU needs at load.
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a b à CPUs
a b K Overclocking
July 25, 2011 1:12:05 AM

I was assuming that the OP had C-n-Q and C1E disabled....Which is what it would do if they were enabled I believe is what your getting at leaps ...BTW do you have LLC enabled
July 25, 2011 8:04:01 AM

lowjack989 said:
I was assuming that the OP had C-n-Q and C1E disabled....Which is what it would do if they were enabled I believe is what your getting at leaps ...BTW do you have LLC enabled


C-n-Q and C1E are disabled and LLC is enabled.

Hmmm, my voltage is reduced in cases 2) and 3). So BIOS voltage is the highest, then idle voltage then load voltage. So 1.4V in BIOS, 1.38v when idle and as low as 1.31v when under load. lowjack989 yours goes up??? What???

So I was thinking when I wrote the OP that if I wanted 1.35v under load I would have to set the voltage incredibly high in the BIOS. And this is with LLC enabled, so thats quite a big voltage droop :S
a b à CPUs
a b K Overclocking
July 25, 2011 8:50:20 AM

Yes, my vcore increases under load no vdroop what-so-ever...heres proof:


http://www.flickr.com/photos/30936964@N05/5973101745/si...


http://www.flickr.com/photos/30936964@N05/5973091657/si...

I use to experience vdroop with other boards but not this one ....My voltages in BIOS are not offset BTW...My BIOS vcore is set to 1.525v...CPUID reads it at 1.536v idle...you can see by the screenies above that at 100% load my vcore is 1.56v...So yes my Set-up increases voltage under heavy load
July 25, 2011 9:11:40 AM

ok cool, but in any case I should be setting my voltages higher in the BIOS to take into account the offset and potential vdroop?

Does that mean its safe to set the voltage in the BIOS higher than the safe voltage for my CPU (1.4v) because when windows (idle or load) it is less than this?
a b à CPUs
a b K Overclocking
July 25, 2011 9:18:16 AM

Yes I would say set it for the off-set in BIOS
July 25, 2011 1:57:02 PM

lowjack989 said:
Yes I would say set it for the off-set in BIOS


Even if this means setting it above the safe voltage in the BIOS?
a b à CPUs
a b K Overclocking
July 25, 2011 4:36:47 PM

Thats really a decision for you to make...Are you not stable at your current settings?
July 25, 2011 7:54:44 PM

Well I thought I was as I have been running these settings for about 6 months now after passing both 10 runs of Intel Burn Test and about 8 hours of Prime95. But the other day I ran Intel Burn Test to remind myself of temps and it failed!!!

tbh, it seems COMPLETELY random to whether it fails or not, I am a little lost.

But this is the reason I asked the questions in my OP. You see I thought I was stable at 3.5v but then looking at my Vcore, its actually running at 1.30v-1.31v when under load. So, I was thinking maybe there is room to increase the voltage.
a b à CPUs
a b K Overclocking
July 26, 2011 2:07:02 AM

What is the PLL voltage? Your Power supply could be getting weak....As far as the vdroop I usually compensate for that offset through BIOS *JUST BE CAREFUL*....If you were stable before I would lean towards a hardware component failing or overheating
July 26, 2011 8:06:00 AM

my PLL is set to auto (about 1.79v) .

Actually yes, I think there is a problem with my PSU. I have been discussing this in another thread. Basically ever since I go my GTX570 it has started making a strange electrical buzzing sound when I game. This is really high pitched and very annoying. Its 650w, so i dont think it is being over powered or anything, but as people have pointed out, this doesn't mean there isn't another problem with it. I have had it just over a year now.
July 27, 2011 1:14:03 PM

Im getting a new PSU at the end of the week so I will let you know what happens! Thanks tho....
!