In the graphic on this slide, the distribution of the surface temperatures is shown. Looking at the flow vector field in a center cross section, on the left, the thermal simulation reveals a zone below the fan motor where a no flow condition can be identified. This behavior is seen for all axial fans used in this type of application. Thermal imaging shows the highest temperature directly at the contact area between CPU and heatsink. The heat is transported inside the heatsink material via conduction and from the surfaces to the air via convective heat transfer. As a consequence of still air below the fan motor, no heat is removed from the heatsink fins in this area and no cooling occurs. The temperature is increasing as shown on the right hand side of the graphic. Many factors, including material, fin design, air velocity and surface treatment, will influence the thermal performance of a heatsink.