Why does Alan Wake 2 stutter on Onda 9D4-VH-D board?

Lighting transitions in Alan Wake 2 caused frame rate fluctuations on my Onda 9D4-VH-D, leading to constant complaints. I tried manually adjusting fan speed, which lowered temperature but increased noise, a frustrating compromise. I used the GamePP Fan Curve Configuration Panel to raise speed at 70°C to 1600 RPM and smoothed the curve. Sensors showed motherboard temperature stable at 65-68°C with frame fluctuations gone, and I successfully backed up the configuration via GamePP System Backup Tool.