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just a question. i know raptors contain heatsinks that are build into the drive casing, i guess mainly because of how hot they do get, but im wondering if other consumer hdds have heatsinks too?
In the techical sense, everything is a heatsink.
The issue is: How many watts of heat (joules per second) is the hard drive producing? Whatever that figure is, you have to be able to transfer that amount of heat at the same rate to the atmosphere around the drive. If you don't transfer at the same rate, the hard drive's temperature will go up.
As the temperature of the drive goes up, there becomes a larger difference between the temperature of the drive and the temperature of the air. The larger difference in temperature speeds up the heat transfer.
Thus, eventually an equilibrium is reached where the drive temperature is such that the difference in temperature between the drive and the air has gotten large enough that the heat transfer rate from the drive to the air matches the heat production rate inside the drive, and the temperature now stays steady.
I won't bore you with the heat transfer equation, but the factors that affect the rate of heat transfer from the drive to the air are:
1. The temperature difference between the drive and the air.
2. The amount of surface area that the heat is moving through.
3. The heat transfer coefficient of the surface-air interface.
Thus, the ways to move more heat out of the drive are:
1. Lower the air temperature or raise the hard drive temperature.
2. Increase the surface area of the drive.
3. Increase the heat transfer coefficient.
The Raptor uses a casing molded with metal fins, which increases the surface area of the drive. This increases the heat transfer rate.
Other drives may not have the metal fins, primarily because they don't need them. Those drives produce less heat internally, thus the heat transfer rate doesn't need to be as high. Those drives can get by without increasing the surface area.
The other way to move more heat out of a drive is obvious -- increase the heat transfer coefficient. The heat transfer coefficient between the hard drive surface and the air is low if the air is still. This also causes the air immediately surrounding the hard drive to rise in temperature, decreasing the temperature difference between the air and the hard drive. If the air is moving slowly, the large temperature difference is maintained. When the air is moving quickly, the heat transfer coefficient increases a lot. Thus, we get to our old standby, the fan.
Please note that this discussion involves heat transfer by convection, which is a means of heat transfer where heat moves from a solid into a liquid or gas (in this case, air). There are other methods of heat transfer, such as heat transfer by conduction, where heat moves through a solid, like a metal (this is how heat moves from the hard drive's voice coil to the outside of the casing -- by conduction through the metal). Also, there is heat transfer by radiation, which is how the Sun heats the Earth.