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View Full Version : G752: Undervolt for extreme heat/battery savings!



Googlegot
07-04-2016, 04:12 AM
First off, this is MY experience with MY laptop. You may not see the same results with your laptop. This also puts your warranty into question, so don't do this if you don't want to break your warranty. I am not responsible for your damaged hardware.

That out of the way, I've been undervolting my laptops every chance I get. Every laptop I've owned that has the capability, I've been able to dramatically increase battery life and reduce temperature without sacrificing any performance whatsoever. The tool I use is Intel's own "eXtreme Tuning Utility", which is supported by Intel on all of their processors (not just the -k revisions). On my laptop (G752VL), I have been able to drop the core offset voltage by -175mV, which translates to a 40% power usage reduction, and a 15c thermal output reduction.

Your laptop may not be able to get this low, or it might be able to go further than mine, but it's 100% worth the time and effort.

This guide outlines the process:

https://www.thinkscopes.com/2015/12/24/skylake-overclocking-and-undervolting-guide/

gtan777x
07-04-2016, 12:42 PM
Hi Googlegot. From what I understand the undervolt will only work with a specific application when app profile pairing has been setup and that apps window is in focus?

Googlegot
07-04-2016, 05:17 PM
The app profile pairing is what the guy in the article uses for persistence, but you can just set the voltage and it stays there until your next reboot or wake from hibernation.

To set it persistently, you can use a shortcut to the xtucli.exe application with a couple command switches in the target field. Then, place that shortcut in the "startup" folder in your start menu (the folder is hidden by default but it still exists). I'll post the contents of my shortcut when I get in front of my laptop.

Armesis
07-05-2016, 02:43 PM
This is fine tuning, can be very beneficial, but at the end of the day, we own some serious gaming laptops. I dont think avid gamers are willing so reduce any voltage at all in the slightest fear that it would impede in the performance. Power saving options on the HDD has been known to cause performance drops in some cases.

Dont get me wrong this sounds like good tuning, but maybe it wont go down well with performance laptops.

Googlegot
07-06-2016, 01:57 AM
This is fine tuning, can be very beneficial, but at the end of the day, we own some serious gaming laptops. I dont think avid gamers are willing so reduce any voltage at all in the slightest fear that it would impede in the performance. Power saving options on the HDD has been known to cause performance drops in some cases.

Dont get me wrong this sounds like good tuning, but maybe it wont go down well with performance laptops.

Armesis, I appreciate your skepticism, and totally understand where you're coming from. However, your conclusion is incorrect.

I grew up in a town centered around silicon production, and built several PCs with input from two electrical engineers specializing in silicon engineering, and this is what I learned from them about undervolting when I asked them:

When undervolting, the only thing you are doing is possibly reducing stability of the laptop. Undervolting cannot reduce performance, as the processor is still running at the same clock rate. On the contrary, as long as the laptop is stable with the undervolt, it can reduce throttling that occurs when the cpu begins to heat up.

Processors are generally run at a higher voltage than is necessary as this can increase reliability of lower binned silicon (lower end cpus, basically). CPU transistors become more reliable the more voltage that is applied (to an extent, they can burn out at too high of a voltage), which is why overclockers overvolt their CPUs for more performance. Manufacturers also set voltages higher than what is required by their high end silicon to increase yield, and allow more CPUs to be made from the same silicon.

Core i7 processors are bin 0 and 1 processors, which means they are the best stock of the wafer. Basically, they are about as perfect as Intel can reasonably mass produce, and that voltage margin they apply across all bins can be reduced a good bit without loss of stability.

The amount that you can undervolt varies by individual processor, but it can usually be a fair bit depending on how close to the center of the die it was when cut.

If you like, I can post some benchmarks to prove my point, but I can promise you right now that as long as your laptop is stable with the undervolt in place, you will not lose performance. You will gain battery life and rather dramatic heat reduction, though.

EDIT: Here is a link to a screenshot of the heat reduction from undervolting my laptop. Before undervolting, the temperature was 92c (red box), after undervolting, the temperature dropped to 77c (white box). Note the green box stating -175mV, and the yellow box showing 3.1ghz (the max turbo boost core frequency with all 4 cores maxed out. This was running prime95.

http://imgur.com/V0ZleUp

Googlegot
07-06-2016, 02:19 AM
Hi Googlegot. From what I understand the undervolt will only work with a specific application when app profile pairing has been setup and that apps window is in focus?

Here is my shortcut target string:

"C:\Program Files (x86)\Intel\Intel(R) Extreme Tuning Utility\Client\XtuCLI.exe" -t -id 34 -v -175

This reduces core voltage by -175mV (adjust the number on the end for your max stable undervolt)

FlashGear
07-07-2016, 03:01 PM
Exactly what I was looking for.

Thanks!!

0% performance loss, temps went from 97-100' down to 77-83'

Sitting on -185mV stable Prime95 at 83'c for 3 hours +-

Bali505
05-24-2017, 05:36 PM
Very interesting! Thank you :)