Wouldn't that depend on the sink? If they can cool down to the water, then running a water-water-heatexchanger would require less power (due to better heat transfer) than simply cooling it to the air.
Same I guess if they could use evaporation to do some of the cooling.
Just seems like a really complicated setup to use unless you were going to be saving enough power to make all the complexity worth it. Remember you have to put a water block on each card and design a pump and piping system that will run through all of them.
Same I guess if they could use evaporation to do some of the cooling.