Described herein are devices, systems, methods, and processes for an efficient liquid cooling system for electronic components mounted on a printed circuit board (PCB). The system utilizes PCB through holes to carry a liquid coolant. The cooling system includes a coolant loop through which a pump circulates the coolant. A cooling sub-assembly includes a cooling channel thermally coupled to the component to be cooled. The cooling sub-assembly further includes a coolant supply PCB through hole that carries the cooled coolant from a supply manifold on the bottom side of the PCB to the cooling channel on the top side of the PCB and a coolant return PCB through hole that carries the heated coolant from the cooling channel to the return manifold on the bottom side of the PCB. The cooling system includes a control system for coolant distribution that can react to component temperatures.