A low profile heatsink is a device installed inside of a computer’s tower, or case, to keep the central processing unit (CPU) or other chip on the motherboard cool during use. Low profile simply means that the heatsink is made to be smaller for easier installation and use in computers that have smaller towers or may have quite a bit of other hardware inside that takes up space. A low profile heatsink can also be made to be quieter than some other heatsinks, since the noise made by a larger heatsink with a powerful fan can be annoying.
The chipset and CPU inside of a computer typically produce a good deal of heat during use, and this is especially true when they have been overclocked by a computer user. In order to keep this heat from damaging the chips, a heatsink is installed onto the chip or CPU. This heatsink works through heat transfer, by coming into contact with the chip and conducting heat away from the chip and into the heatsink itself. The heatsink is then cooled through the user of a water cooling system or fans that run air across the heatsink, transferring the heat and then moving that heat out of the computer.
A low profile heatsink is simply a specific type of heatsink made to be smaller and usually designed to be quieter. The heatsink is typically a crucial part of a computer; most motherboards even have a basic input/output system (BIOS) that includes a protocol to not allow the computer to start up if a heatsink is not properly attached. This is because an overheating CPU or chip can quickly be damaged and even begin to melt on the motherboard, causing further damage. A low profile heatsink allows a CPU or chip to remain cool and not damage the computer, but not take up as much space as a regular heatsink.
This can be quite useful for computers with a smaller case or for computers in a custom case that may also use a small motherboard. A low profile heatsink is typically designed to be as small as possible, and if it has a fan on it the fan will also typically be quite small. Size does not necessarily determine effectiveness with heatsinks, and even a low profile heatsink can effectively cool an overclocked CPU if it is of high quality. There are a number of different technology websites that provide reviews of various heatsinks, including low profile ones, to give consumers a sense of which heatsinks tend to work best.