Design

There are many companies that produce heatsinks for the various parts of your computer. Each of these companies incorporate slightly different designs into their products. As with the design of virtually every piece of your computer, there are many different variables that need to be taken into consideration when crafting a heatsink, such as:

Surface Area and Contact
-Generally speaking, the more surface area a heatsink has, the better. However, if you simply make a huge, flat piece of aluminum with a large surface area and plop it down onto your processor, you will get lousy results. The areas of the two contact surfaces would be dramatically different, leading to inefficiency. This is why we see fins, and in some cases, hundreds of plates of material in tight formation.

Size
-Large heatsinks will usually always perform better, but in a computer case there is limited space. Do you sacrifice the effectiveness of your heatsink for practicality?

Thermal Conductivity
-The material used in the construction of your heatsink will play a large role in the rate at which heat can be transferred from the component. Aluminum and Copper are the most frequently used materials for computer heatsinks because the two metals are fantastic thermal conductors.

Air Flow
-A heatsink being used without the assistance of a fan is generally less effective for several reasons, the most prominent being the “Laminar Effect”: Air will move slower near the surface of a heated object than it will when farther away. That means the heat will not transfer as rapidly as it would if there was air blowing directly onto the surface (fins) of the heatsink. Thus, mounting a fan onto your heatsink will drastically increase its ability to transfer heat. However, the size and speed of the fan are also considerations, as they directly affect the level of noise and amount of moving air cycled through the cooling apparatus.

Emissivity
-Without going into too much detail, emissivity controls the amount of heat a surface can transfer as a result of thermal radiation. Since radiation occurs on the surface of an object, the color of the object is usually the big factor in determining emissivity. Dark, drab, matte surfaces will invariably transfer more heat than polished, shiny ones.

Heat Pipes
-Although heat pipes really deserve their own entire category as a cooling device, they are commonly incorporated into the design of convection heatsinks these days, so we will include them here. Heat pipes operate on the principles of evaporative cooling and latent heat. The heat pipe, in essence, is a long tube made out of thermally conductive metal (usually copper) and that is filled with liquid coolant. One end of the heat pipe is fixed to the source of heat, while the other end is incorporated into some kind of cooling device (usually the fins of a heatsink). When heat is absorbed on the end of the heat pipe that is attached to the heat source, the fluid inside the pipe evaporates to its gaseous state, causing it to travel to the other end of the pipe, and away from the heat source. At the opposite end, it is cooled by way of the cooling apparatus (heatsink fins), and returns to its liquid state to flow back towards the heat source. The pressure differences inside the confined pipe allow for the rapid cycling of coolant throughout the system (gas has more volume than liquid, so in a confined space this means a large pressure differential). Depending on the latent heat capacity of the coolant used, and application of the device, heat pipes can be extremely effective at transferring heat.

Bottom Line

Convection heatsinks are the most commonly used type of cooling device in computers because they are relatively simple to produce and are reasonably priced. When used in conjunction with thermal compound to aid in the transfer of heat between component and heatsink, they can be tremendously effective at cooling off your PC. Many heatsinks currently available on the enthusiast level incorporate heat pipes in their design.