Heat Transfer

Just putting a nice heat sink onto your processor is not always enough. You have to make sure the heat sink is firmly connected to the processor so that heat is totally transferred from the processor core to the heat sink. Failure to adequately do this can lead to heat related problems even though you have a nice cooling fan.

Most retail-boxed processors come with heat sink/fan combinations already attached to the processor. These setups are convenient because you do not have to worry about buying a fan that is adequate for your processor and don’t have to worry about ensuring full contact.

Many users, though, find themsleves needing to fasten the cooling device in themsevles. With some chips (older ones) you can simply attach a good heat sink & fan to the chip by clipping it onto the processor socket or processor case (depending on which processor form factor you are using). On newer processors, this is not enough. In this case, a special chemical called heat sink compound is placed between the heat sink and the processor core for better heat transfer. This is a white paste that is spread onto the processor core. Very little is needed, just enough to fill in the gap of air that would be there without the compound. If you use too much, it could not only lead to a mess, but you can actually hinder heat transfer. This compound is found at most electronic stores. Many cooling devices and sometimes motherboards themselves come with a small amount of it.

Also worth mentioning, some heat sinks come with a small pad underneath to facilitate heat transfer. On these setups, heat sink compound is not necessary. But, upon removal of the processor at some later date, that pad will be melted and remnants of it will be attached to both your processor and your heat sink. Before re-installing, you need to completely clean off this old pad and replace it with heat sink compound. But, these pads are convenient for first time installations.

Quality Parts

Active heat sinks have a reputation for being cheaply made and prone to failure. A plain-jane CPU fan goes for about $5. Such a fan uses a cheap sleeve bearing motor. This has a short lifespan and can sometimes get rather noisy as they grow old. When buying a new CPU fan, make sure it uses a ball bearing motor. These also usually come with a nice warranty. These fans are more expensive, about $20-$30. Some of them are also pretty large and quite heavy.

Peltier Coolers

Peltier coolers are a heavy-duty way of keeping the processor cool. They work like a tiny air conditioner that does not use fluids, moving heat from one side of the cooler to another so that one side is hot and the other is cold. Obviously, the cold side is placed on the processor. The hot side is pointing away from the chip and has a heat sink on it. The system literally pumps the heat off of the processor.

This system is not needed for most processors. It has no moving parts, therefore it is not prone to failure. But the system can be hard to get working. Most people can avoid it. The speed freaks who engage in overclocking are the only avid users of the Peltier cooler. They run the chip faster than it is designed, therefore making lots of heat.

The prices for these coolers range from around $30 to about $70. The performance of the units vary greatly as well. When purchasing a Peltier cooler, take into account the price, its performance, and how large it is.

Socket 370/Socket A

When Intel created Socket 370, it created it with backwards compatibility of cooling in mind.  Socket 370 is physically the same as Socket 7 to a point where it can use the same heatsinks.  Socket A is totally different, and requires a rework of the base in order to make clearance for a portion of the socket structure itself.  Because of this, Socket 370 heat sinks can not work on Socket A chips, but Socket A heatsink can work on Socket 370 chips.

Besides the actual heatsink concern, there is also a slight concern of the “feet”.  Because the actual contact area between the CPU and the heatsink is so small, some heatsinks for Socket 370 chips come with little feet pre-attached.  Socket A chips already have the feet on the chip, therefore giving no need for feet on the heatsinks.  If there are feet on your heatsink, be sure to remove them before putting it on a Socket A chip, otherwise the heatsink will not contact the super hot Socket A chip, and cause it to burn itself into heaven in a matter of moments.

Shims

Shims are becoming increasingly popular today. Basically, a shim is a small piece of metal that will sit on top of the processor itself and spread the weight of a hink sink across the width of the processor. The reason for this is because people have experienced the dreadful experience of having crushed their processor core under the weight of a hink sink. Modern socketed processors have the core of the processor often sticking up slightly from the rest of the packaging. When the hink sink is placed on top of the processor and clipped down to the socket, the pressure of the clips exerts much more pressure downward that simply the weight of the heat sink. With too much weight, you can actually crush the core.

So, a shim is placed on top of the processor, with the top of it being flush with the level of the core. This means that the heat sink has a lot of surface area on whcih to sit. One thing that is important here is to be sure any shim you use is designed specifically for the processor you are using. There are gaps in shims placed specifally to allow space for the cache bridges on top of the processor. These bridges can be shorted if the metal shim is placed on top of them, causing damage to the processor. On top of this problem, a mis-aligned shim can also cause the heat sink to not make fully contact with the core, which will inevitably lead to overheating.