Even if you can keep the water at room temp, At temps very high the water will not cool the Cpu/Gpu's as the heat doesn't transfer 100% of the heat to the water molecules, You will hit a wall where the only difference made will be to use a chiller unit or Dry ice, Also you only need a 360x60mm Rad with GT14's for that i don't think you would even see an improvement with a 480x60 rad over a 360, You'll never get below room temp and 2C lower on the water doesn't mean 2C lower on CPU and GPU unless you have 100% heat transfer which is psychically impossible.
Example: room @ 19C
Water 20C, Cpu 250watts of power draw, Temp 60C
Water 20C, CPU 350Watts of power draw, Temp 80C
Water+chiller 5C, CPU 350Watts of power draw, Temp 72C
(Just an example not tested results, Although i'm sure someone has done this, I tested this years ago results where similar to example)
Diminishing Returns apply when stacking Rads over the amount of Heat wattage you want to remove.
Not as clear as i possible can make it, But i'm at work.
P.S no Fans on Rads doesn't work you hit a equilibrium after X time Rad's are designed to have airflow.