heat pipes and heat spreaders
A heat pipe is a sealed tube containing some type of coolant (water or ethanol) The heat source evaporates then condenses at a cooler point in the pipe and flows back toward the heat source. The cool parts of the pipe are kept so by convection. This mechanism is more effective than a simple heatsink and fan assembly, It is necessary for a CPU that runs,
particularly hot or where there is not much space for airflow within the chassis A dual heat pipe has two tubes, providing better cooling.
A heat spreader uses the same design but is flat container rather than a pipe, This design is better suited to portable computer.
If use without fans. heat pipes and spreaders are classed as passive cooling.