By the way, can anybody suggest tips for powering up the pump for filling without turning on the rest of the system in order to conduct the leak tests.
I have not looked into water cooler but I guess the pump runs off the psu in which case could you not just connect green wire and any black wire on the 24 pin cable to turn the psu on with only the pump plugged in. I am sure someone will come along with a better answer if there is one though.