You likely have a setting for fan ramp time in your bios, usually in seconds. So setting your pump to always run at 100% and your fans to ramp slowly, say 10 seconds or longer, and using a minimum fan speed that is as high as tolerable would likely work as a no-additional-code solution.

Looks pretty cool, the self-calibration routine is very nice too.

My only worry is that rapid changes in pump speed might cause extra mechanical stress or wear on the pump, but I have no data to back that up. I've just heard that water pumps sometimes behave in counter-intuitive ways - e.g: sometimes running at a higher speed is better for longevity than a lower one.

It would have been neat to include cpu freqency in your charts along side temperature and other things.