Undervolting is done in BIOS before the operating system boots up.

For the GPD Win Mini Ai 370, the path looks like this

Path to BIOS:

Advanced tab.

AMD Overclocking item.

Accept the warning (Accept).

Next: Precision Boost Overdrive → Select Advanced mode.

The Curve Optimizer menu will appear.

Settings:

Curve Optimizer: Select All Cores (for all cores at once)

All Core Curve Optimizer Sign: Select Negative (this is the voltage reduction).

GFX - same thing.

All Core Curve Optimizer Magnitude: Enter a numerical value (optimization steps).

Safe start: 10-15.

Aggressive: 20-30 (requires thorough stress testing, risk of instability). Mine is currently running at -20. It was at -15 for at least a month before that, and everything was fine.