How do I stop my CPU from downclocking during Alan Wake 2 rendering?

I was stuck in a dark forest scene when my CPU frequency dropped from 5.2GHz to 4.6GHz. The water temp hit 72°C, and I was furious. I tried just boosting fan speed, but it barely helped. Then I used GamePP Fan Curve Config to raise the pump base speed to 2000 RPM and set radiator fans to ramp to 1600 RPM at 60°C. AIDA64 confirmed the temp stayed at 65-68°C and frequency held at 5.1-5.3GHz. It finally saved my render.