Undervolting your graphics card means tweaking the voltage the chip uses at a chosen frequency. Chips usually have a very conservative voltage/clock speed ratio, meaning you can reduce the voltage a lot without reducing the clock speed by a lot. Your card will draw less power, run cooler and more silent and be more power efficient.
Important: This guide only applies to Nvidia cards.

Required software

To start off, we need software that allows voltage control of the graphics card. Our software of choice will be MSI Afterburner. Head over to the MSI website and download the program.

Make sure you are running the latest version of your graphics card drivers, either studio drivers or game-ready drivers.

Enabling voltage control

Install and open up MSI Afterburner. Initially, voltage control is disabled, so we have to enable that first. Navigate to the Settings menu and check the 'Unlock voltage control' checkbox on the General tab. You may also want to check the 'Start with Windows' and 'Start minimized' checkboxes so that your settings are applied automatically each time.

Setting a custom voltage curve

Close the settings dialog and press CTRL+F to open the voltage curve window. This shows a graph illustrating the voltage the card uses at each clock speed interval.

What we want as a result is to lock the frequency at a certain clock speed. As an example, we will use a virtual ratio of 1964 MHz at 1000 mV.

First, we lower the complete curve under 1964 MHz. Alt+click the curve, and you can lower the complete curve at once.

Next, drag the dot at 1000 mV back up to 1964 MHz. When you save these settings, you will see that the curve changes, and all the dots above 1000 mV will be at 1964 MHz as well. As a result, your card will boost to 1964 MHz max, while never using more than 1000 mV.

Note: The examples are fictive numbers and will probably not work very well for your card. Please refer to the end of the article for references per chip.

Drag the initial curve down using Alt+click.
Drag the target mV point to the chosen clock speed.
After saving your settings, your curve should look something like this.

Testing your settings

Testing the settings is best done using benchmark software. The most popular free software is probably Unigine Superposition or Furmark. Make sure to run the benchmarks at least 5 to 10 minutes to test for stability. When the settings are not stable, you may experience artifacts or driver crashes. Increase the voltage or decrease the clock speed when you do and run the test again, to find the optimal balance.

Reference voltage/frequency ratios

In order to not go in blind, I have tested popular cards for undervolting so you have a reference for what works well for me. I have focused on preserving as much of the performance as possible, so it should be within 5% of the original performance, while still using much less power.

Card Clock speed (MHz) Voltage (Mv)
RTX 4060 2722 925
RTX A2000 1600 750
RTX 4000 SFF 1700 725