H80i CPU Cold Plate and Water Chamber
The lower water chamber of the CPU cooler assembly has an inlet channel in the upper middle of the assembly fed by the pump output through the upper barb (in the picture) with two outlet channels in the lower right and lower left corners feeding the outlet barb. The o-ring along the outside edge of the chamber sits against the CPU cold plate to make a water tight seal just inside the screws mounts. Along the middle right outside of the assembly is a thermistor that rests against the cold plate surface for cold plate-based temperature readings.
The CPU cooler assembly's impingement plate is made from white rubber. When seated against the assembly, the upper side of the plate forms a channel that directs water from the pump outlet through the center groove onto the center of the CPU cold plate. The function of the impingement plate in this case is two fold – to create an input channel for water from the pump and to accelerate the coolant flow across the directed portion of the cold plate. In high-end water blocks, the included impingement plate is made from steel or aluminum with the plate sealed to the inlet channel using a rubber o-ring. The H80i's rubber-based impingement plate is effective without the need for a metal-based plate because of the low pump pressure. In this design, the impingement plate's coolant acceleration is key to the cooler's CPU heat collection and dissipation.
The top of the CPU cold plate consists of fine copper fins oriented perpendicular to the impingement plate's channel. The center indented channel sits directly under the impingement plate slit acting to control the water flow and force it through the thin copper channels. The outer collection channels feed into the outlet barb leading to the radiator. The coolant shoots through the impingement plate into the cold plate's center channel and is forced through the thin copper channels to the outer collection channels. The thin-finned channels give the coolant increased surface area from which to absorb heat from the cold plate and CPU while traveling to the outer collection channels. The impingement plate seals the center of the cold plate so that the coolant flows in the correct direction and efficiently through the copper finned channels on the cold plate.
The bottom of the CPU cold plate is flat and polished so that is it free of surface imperfections. Notice that the hold down screw holes are countersunk into the surface at that the screws do not effect the flatness of the cold plate's surface.