[derefr]

> at the end of the day, dissipating heat is a function of the radiator fin area and air movement, the water is just a working fluid to move the heat to the radiator fin

...in a fluid-recycling system (as all consumer PC cooling is.)

Water cooling is a lot more efficient than air cooling, in a fluid exchange system. Like if your HPC data-center is on the ocean, and you can just pump in cold ocean water, "spend" it by heating it up, and then pump the hot water to an outtake far-enough away that it's not heating up your intake water.

(An even-denser fluid would work even better, but we don't have oceans of even-denser fluids laying about.)