An apparatus for cooling a plurality of rack-mountable servers containing heat generating electronic components in a server room including a dielectric liquid cooling apparatus located inside the tank and a secondary cooling apparatus comprising a remote heat exchanger and at least one pump. The volume of dielectric liquid coolant comprises at least one passage in the tank that is outside of the vertically oriented rack-mountable servers. When the at least one pump is operated to move the dielectric liquid coolant vertically across the heat producing components on the vertically oriented servers, a circuit is formed in which a first portion of dielectric liquid coolant is moved vertically upward across the heat producing components on the vertically oriented servers and then downward outside of the rack mountable servers in the at least one passage, while a second portion of the dielectric liquid coolant flows out of the tank.