A cooling device for cooling a chip, a server with such a cooling device, and a rack are disclosed. The cooling device comprises a cooling layer that is divided into multiple cooling regions; and an internal region that includes a vapor separation core. Two-phase coolant that enters a first cooling region of the cooling layer is converted to mixed fluid due to heat extracted from a corresponding region of the chip. The mixed fluid is elevated to the vapor separate core, which separates vapor from liquid in the mixed fluid. The vapor exits the cooling device while the liquid is transported to a second cooling region in the cooling layer. The cooling device can be used with a condenser in a server to form an internal server loop, and can be connected to a rack to form a main fluid loop. The two coolant recirculation loops are used together to maintain a predetermined liquid balance in the cooling device.