Undervolt Nvidia Card Mining – Saving Your Power

Efficiency is important in mining because it determines your profitability. Electricity and cooling equipment are the major costs in mining. This blog will introduce the method of reducing power consumption and heat by undervolting Nvidia graphics cards. After undervolting, the power consumption of my GTX 1080 Ti, mining Lyra2REv2, significantly drops about 30% and fan speed decreases 33% when default fan speed is used. It also runs much quieter with undervolting.

Here is the comparison between default setting and undervolting,
This is default setting,

The hashrate is around 62.5 MH/s. The card consumes 103.4% of TDP (TDP for GTX 1080 Ti: 250 W, 103.4% is 258.5 W) and the fan runs at 1795 RPM when the card is 69 °C.

This is undervolting,

The hashrate is around 60.5 MH/s. The card consumes 73.9% of TDP (TDP for GTX 1080 Ti: 250 W, 73.9% is 184.75 W) and the fan runs at 1193 RPM when the card is 64 °C.

What you need for undervolting:

1. Overclocking Utilities (MSI Afterburner is recommended, link: https://www.msi.com/page/afterburner)
2. GPU Monitoring Utilities(GPU-Z is recommended, link: https://www.techpowerup.com/download/techpowerup-gpu-z/)

Read the entire guide thoroughly before starting to undervolt

First,
Open MSI Afterburner and click setting.

(Note-1: the screenshot is version 4.4.0, the newest version is 4.4.2 at the time I write this blog, but you can still follow this guide to undervolt your GPU)
In the setting window, select "Unlock voltage monitoring"

Click "OK" to finish setting and you should be able to see the voltage value in the right side of MSI Afterburner.
GPU-Z is another way to monitor the GPU core voltage

"VDDC" is the core voltage.

Second,
Hit CTRL + F in MSI Afterburner or click this button,

And you should see this "Voltage/Frequency curve editor" window below.

The x-axis represents the voltage in mV (millivolt), the y-axis represents the frequency in MHz (megahertz). The dotted line indicates the current value the GPU runs at.
For example, at 981 mV, my GTX 1080 Ti will run at 1873 MHz.
The higher the voltage your GPU runs at, the more power it consumes and the hotter it is. So in order to reduce the power consumption and heat output, all we need to do is to undervolt it by editing the curve. You can use your mouse to drag those points on the curve or use your mouse to select the point and use your arrow key to adjust it.
###Caution: DO NOT SET FREQUENCY TOO HIGH###
###Caution: DO NOT SET VOLTAGE TOO LOW###
It is not recommended to go below 200 mV than default
You can mine with the default setting to get the voltage. The voltage might be in range.
For instance, with the default setting, my GTX 1060 is constantly at 1050 mV, but my GTX 1080 Ti is at a range of 950 mV-1050 mV. For the safety and stability of graphics card, I would not go below 850 mV with my GPU and I lower the frequency at 850 mV to ensure stability.

Tuning:
You can change the voltage point by point, for example, my GTX 1080 Ti runs 1873MHz@981mV and the next point below it is 1860MHz@975mV. You can change the point of 1860MHz@975mV to 1873MHz@975mV or you can lower the frequency at 981 mV to 1860MHz@981mV because your GPU won't waste energy on no frequency improvement. Although you set 1860MHz@975mV and 1860MHz@981mV, the GPU will run 1860@975mV. After finish setting the point at 975 mV, go to the Third step to check stability. If there is no issue, you can adjust the next lower point, which, on my GTX 1080 Ti, is 962 mV.
If there is a problem with stability, go back to point at 975 mV and lower the frequency. Let's assume that you have a problem with 1873MHz@975mV, you can step down 10 MHz, 1863MHz@975mV, and you need to change the point at 981 mV to 1863MHz@981mV as well. Otherwise, your GPU will run 1873MHz@981mV because there is a frequency improvement. Bear in mind that your GPU will not waste energy on no frequency improvement. So your curve should be horizontal from the point where you set the voltage you want to the point where the default value is. Below is the final curve of my GTX 1080 Ti.

My GTX 1080 Ti runs at 1809 MHz from 850 mV to 1075 mV. (The line without points indicates the curve you edited last time)
(Note-2: I extend the horizontal line to 1075 mV because my GTX 1080 Ti occasionally jumps to 1063 mV for a second. If you encounter similar situation, you can extend the horizontal line)
(Note-3: If you think it is tedious to begin from the default voltage point, you can start from the point that is about 50 mV lower than the default)

Third,
Drag the "Voltage/Frequency curve editor" window away or close it and click the check mark on MSI Afterburner after you finish setting,

Run mining software to check stability.
It is recommended to mine at least five minutes to check stability.
If it crashes, go back to the Tuning part of the Second step.

Final Thoughts,
If you want to restore all the changes back to default, click this button.

You can run at a default frequency or higher while undervolting to achieve no loss in hashrate or gain.
Higher Freqeuncy might result in higher hashrate and higher power consumption and the relationship among them usually are not linear. Sweet point can be found by trying different values of frequency and voltage. The GTX 1080 Ti, running 1809MHz@850mV, is only used for an example. This method should work with many Nvidia Cards.
For owners of AMD cards, I suggest editing the bios and undervolting with Radeon WattMan.
I might write a guide for AMD GPU in the future.

This guide is not all-encompassing. If you have any questions or thoughts, leave comments below. I am glad to help you.

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