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Why dose the CPU Core Voltage float up and down a little at a steady state clock speed?

ssote
New Contributor II
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Why dose the CPU Core Voltage float up and down a little at a steady state clock speed, is it because of VRM spread spectrum or another Intel specification I don't know about?

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idata
Employee
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Hello wingman99:

 

 

The reason for that is because of the processes that are running in the background, it is very unlikely for the clock speed to be stable, since there is always something running, so, it is expected to for it to go a little bit high or low depending on the work load.

 

 

Any questions, please let me know.

 

 

Alberto
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ssote
New Contributor II
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However when I look at the CPU load I have it running full load with prime95 at full clock speed. Dose it have to do with dynamic voltage from the VID sending comands VRM and if it does then why?

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idata
Employee
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Hello wingman99:

 

 

In regard to your inquiry, I just wanted to let you know that it is expected for the processor core voltage to fluctuate, it was the way it was design, even if the clock speed is steady.

 

 

As long as the PC is not getting freeze or giving you any kind f problems, then the processor should be fine.

 

 

Additionally we always recommend to use the PC at stock configurations, you can always do that by setting the BIOS values to default.

 

 

Just in case, on the following link you will find a tool to test the processor, if it passed the test it should be fine, second option to the left to install it:3

 

 

https://downloadcenter.intel.com/download/19792/Intel-Processor-Diagnostic-Tool https://downloadcenter.intel.com/download/19792/Intel-Processor-Diagnostic-Tool

 

 

Any questions, please let me know.

 

 

Alberto

 

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ssote
New Contributor II
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Intel Corporation wrote:

Hello wingman99:

 

 

In regard to your inquiry, I just wanted to let you know that it is expected for the processor core voltage to fluctuate, it was the way it was design, even if the clock speed is steady.

 

 

As long as the PC is not getting freeze or giving you any kind f problems, then the processor should be fine.

 

 

Additionally we always recommend to use the PC at stock configurations, you can always do that by setting the BIOS values to default.

 

 

Just in case, on the following link you will find a tool to test the processor, if it passed the test it should be fine, second option to the left to install it:3

 

 

https://downloadcenter.intel.com/download/19792/Intel-Processor-Diagnostic-Tool https://downloadcenter.intel.com/download/19792/Intel-Processor-Diagnostic-Tool

 

 

Any questions, please let me know.

 

 

Alberto

Is there a way you could find a technical explanation for the reason?

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idata
Employee
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Hello wingman99:

In regard to your request, in order to provide the most accurate information, please provide the model of the processor so we can search for the specifications of it?

Any questions, please let me know.

Alberto

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idata
Employee
1,852 Views

Hello wingman99:

 

 

I just wanted to verify if you saw the information we are requesting above? It will be very helpful for us to better assist you.

 

 

Any questions, please let me know.

 

 

Alberto

 

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ssote
New Contributor II
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Intel Corporation wrote:

Hello wingman99:

In regard to your request, in order to provide the most accurate information, please provide the model of the processor so we can search for the specifications of it?

Any questions, please let me know.

Alberto

i7 6700k

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idata
Employee
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Hello wingman99:

 

 

Thank you very much for providing the model of the processor.

 

 

On the following link you will find the data sheet for the Intel® i7-6700K processor, and in there you will be able to get information about the voltage of the processor, you can reference pages: 16, 39, 42, 44, 52, 53 and 61:

 

 

http://www.intel.com/content/www/us/en/processors/core/core-i7-6xxx-lga2011-v3-datasheet-vol-1.html http://www.intel.com/content/www/us/en/processors/core/core-i7-6xxx-lga2011-v3-datasheet-vol-1.html

 

 

The data sheet has two parts, here is the second one in case you want to check it, but I did not found much information about voltage in there:

 

 

http://www.intel.com/content/www/us/en/processors/core/core-i7-6xxx-lga2011-v3-datasheet-vol-2.html http://www.intel.com/content/www/us/en/processors/core/core-i7-6xxx-lga2011-v3-datasheet-vol-2.html

 

 

Please let me know if the information you were looking for is in there, or if you need further details about this matter.

 

 

Any questions, please let me know.

 

 

Alberto

 

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idata
Employee
1,852 Views

Hello wingman99:

 

 

I just wanted to verify if you found the information you requested on the links provided above, and also if you need further details about this matter?

 

 

Any questions, please let me know.

 

 

Alberto

 

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ssote
New Contributor II
1,852 Views

Thanks for the links, however I'm not looking for specifications.

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idata
Employee
1,852 Views

Hello wingman99:

 

 

Thank you for letting us know that information.

 

 

In this case, we will do further research in order to provide more documents and details about this matter.

 

 

As soon as I get any updates, I will post all the information on this thread.

 

 

Any questions, please let me know.

 

 

Alberto

 

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Ronny_G_Intel
Community Manager
1,852 Views

Hi wingman99,

I would say that this is probably due to power saving.

Are you using anything similiar to Open Hardware Monitor*? What are your readings?

Anything else we need to be worried about it? If everything is working as expected then It is power saving I would think.

Thanks,

Ronny G

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ssote
New Contributor II
1,852 Views

I also belie it is power saving features, however when I have fixed core voltage there is still small fluctuation, I'm just wondering why today's VRM's are not rock solid?

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CCris2
New Contributor II
1,852 Views

Hi wingman99 ,

Power is fluctuating because even if CPU is at max frequency, it does different operations, and even if each core is fully utilized, or only parts of each of them are utilized the frequency goes up

Each transistor in CPU is a consumer and voltage depends of how many transistors are on or off.

Even if you want you can't have full voltage stabilization. Even on the best stabilizers, on load voltage varies.

Things are more complicated, this is all I can tell you for your understanding.

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idata
Employee
1,852 Views

Hello:

 

 

Thank you very much to Ronin for the comments posted previously.

 

 

To wingman99:

 

 

I just wanted to check if the information above was useful for you and if you need further assistance on this matter?

 

 

Any questions, please let me know.

 

 

Alberto

 

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ssote
New Contributor II
1,852 Views

No, however I know all you can do is read off of the Data sheets.

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CCris2
New Contributor II
1,852 Views

Hi wingman99 ,

This is not about datasheets, this is about physics. Imagine the power line of your house. When you have more consumers the voltage will be slightly lower when you have less consumers the voltage will go a bit up. Even if the power is rated at 220V or 110V it will never exactly that voltage, because on that line there are in the same time more houses connected and not all of them have the lights on, or off.

This is the same with CPU's, not all transistors are on or off in the same time in one core of the CPU, and there are millions in there. When there are more transistors on voltage will go down, less transistors on voltage will go up. Its very simple.

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idata
Employee
1,852 Views

Hello:

 

 

Thank you very much Ronin for the comments above, that is a perfect example of how the voltage works, and that information will be very useful for us and for all the peers viewing this thread.

 

 

To wingman99:

 

 

I hope the explanation provided previously was helpful for you in regard to this matter and that you now have a better understanding about this subject.

 

 

Regards

 

 

Alberto

 

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ssote
New Contributor II
1,852 Views

Ronin wrote:

Hi wingman99 ,

This is not about datasheets, this is about physics. Imagine the power line of your house. When you have more consumers the voltage will be slightly lower when you have less consumers the voltage will go a bit up. Even if the power is rated at 220V or 110V it will never exactly that voltage, because on that line there are in the same time more houses connected and not all of them have the lights on, or off.

This is the same with CPU's, not all transistors are on or off in the same time in one core of the CPU, and there are millions in there. When there are more transistors on voltage will go down, less transistors on voltage will go up. Its very simple.

I have a digital multi meter and my outlet voltage does not fluctuate. If it did my PSU can compensate for 12 volt and it does not fluctuate.

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CCris2
New Contributor II
1,671 Views

Hi wingman99 ,

Your outlet voltage does not fluctuate in short time, but if you monitor for a day you will see that it fluctuates. Imagine that on CPU that day is a second ...

And yes PSU can compensate, but if you play a game, that uses intensively your video card, and measure the voltage you will see that the 12V will have a small variation.

On CPU when a transistor is turned on it adds a small impedance and that makes voltage drop and the voltage regulator rises the voltage back. There are also some small voltage stabilizers for each part of the CPU, inside of it, but they can't keep up perfectly with all those millions of very fast transistors turning on and off , that's why you see some voltage variations.

For the voltage to be perfectly stable it needs a voltage regulator with prediction, which needs to know exactly when each transistor is turned on or off to adjust the voltage. That you will never see

In conclusion that small voltage variation is normal and you don't have to worry about it.

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