HEATSINK SURFACE TREATMENT

Aluminum heatsinks are usually anodized; a choice of many colors is available. One might think that black is good, because it is best for heat emission by radiation. This is wrong. Heatsinks get rid of heat by convection (that is, heat is transferred to the air molecules travelling along the heatsink surface - if a fan is involved, we call it "forced convection"). For convection, the color does not matter at all.

Copper heatsinks are sometimes plated with silver or even gold. This is supposed to prevent corrosion and improve thermal characteristics. But actually, the plating is too thin to have any effect on thermal conductivity. It is true that the surface of a copper heatsink may slightly corrode; but since they are operating in a dry environment, and do not have to withstand extreme temperatures, corrosion is not really a problem. During the lifetime of a PC heatsink, the corrosion layer will not get thick enough to have any negative effect on cooling.