When choosing the best computer processing unit (CPU) heatsink for your computer, it is most important to first find a heatsink that fits the build of your current CPU. To determine whether a CPU heatsink fits with the processor, you need to determine its socket. Usually, processor sockets look like a plastic rectangle with a little metal lever on the side that secures and releases the CPU chip. From the available compatible CPU heatsink options, you can then determine whether each CPU heatsink meets your needs for performance, size, and sound levels.
"Socket" is the name for the bed in which the processor is seated, and identifying it is important, because a heatsink made for the wrong CPU socket will not fit over the CPU properly. Socket types are numerous. The only way to determine your socket is to find out the type of CPU and determine the compatible socket. A couple of the most well-known manufacturers of processors and processor sockets include Intel® and Advanced Micro Devices (AMD®). Once you have determined the compatible socket for your CPU, you can use that information to choose the best heatsinks that fit your CPU socket build.
Go to the computer hardware store and look at the heatsink packages for the CPU heatsinks you determined to be compatible with your CPU socket. If you lack a computer store nearby, find the dimensions of each heatsink on the manufacturer's website. With these measurements in mind, make sure the heatsink will fit into your computer case, the metal box that houses your computer parts, with the door to the case closed. Most fan-based heatsinks are fairly compact and will fit into all but the most tightly configured of computer cases. A CPU heatsink that uses a fan can also be called an active heatsink.
Heatsinks that do not use fans are usually called passive heatsinks. Passive heatsinks are usually large metal fixtures attached to a clip that affixes to the CPU heatsink bracket. Because passive heatsinks remove heat from the CPU by conducting it into the metal parts of the passive heatsink, high-end passive heatsinks can be rather large and difficult to fit into a standard computer case. Passive heatsinks can also be much heavier than most active heatsinks, requiring a special heatsink clip and bracket fixture designed to support the heavier passive heatsink. One advantage to passive heatsinks is that their lack of a fan motor assembly makes them a much quieter option for cooling a CPU.