I used the method shown in this video and it worked perfectly. As shown in the video, the important thing to do is to drop the whole voltage curve first by reducing the core clock 200-300 MHz before setting your desired voltage and clock speed point on the curve. When you apply it, the line should be pretty much flat to the right of your set point.
Here’s what my undervolt curve looks like on my 3080 (0.900V @ 1905MHz)
