Cooling is a very important issue in the world of personal computing. Processors today run suprisingly hot. Without any cooling, most processors today would burn up in only a few seconds. Without adequate cooling, processors will still run for a while, but may begin to cause random errors to more serious errors. Some processors, such as the Pentium IV, have internal safety features to protect themselves in such situations. Others, like the current lot of AMD processors, will just sit there and burn up unless your motherboard helps to cover it with alarms.

With the 386 processor, there wasn’t a need for a special cooling system. The chip was slow and did not have many transistors, therefore the air flow from the power supply was enough to cool the chip. With the release of the 486, cooling became an issue. With the slower 486’s, it wasn’t really a big deal, but with the 486DX-66, cooling was an issue. This clock-doubled chip got pretty hot. From then on, chips ran faster and hotter. All chips used today require a special cooling system. How much cooling depends on the processor, the case, and the type of cooling system you are using.

The type of processor is the biggest variable in the amount and type of cooling needed. As a general rule, the newer the processor, the hotter it will run and thus the more cooling capability you will require.

Cooling Problems

A processor that is not cooled enough will show some strange errors. Every processor has a safe range of temperatures that it can handle. Once the temperature gets above that point, one will usually see random error messages. Many times, one will not suspect that cooling is the problem because the error will seem to be coming from another part. Common errors are system crashes, lockups, and surprise reboots. It can also have program errors and memory errors along with many other things. System builders sometimes have problems with initial boot-up because of inadequate cooling. Sometimes the system will power on and then seem to just sit there, actually locking up on boot-up. Always check the cooling situation when this type of thing happens.

There are various ways that you can monitor the temperature of your processor. One of the most common ways is to go into your motherboard’s CMOS and take a look at the temperature screen. Most motherboards now have this feature. It will interface with a small sensor on the motherboard that will monitor the temperature of the chip. This same screen will also show you the fan RPM speeds, voltages, etc. While this can give you useful information regarding cooling, it is worth mentioning here that these sensors are not always the most accurate things in the world. Sometimes you will still be experiencing problems even though the sensor is reporting temperatures that seem reasonable. If you do not want to sit there and stare at your CMOS screen, you can also download some utilities that will show you this information from inside of Windows. Motherboard Monitor is a popular such title.

Heat Sinks

Heat sinks are used in many electronic devices for cooling, but for our purposes here, they are placed on processors to cool them. The operation is simple. It is a piece of metal, usually aluminum or some other metal highly condusive to heat, with large fins protruding outward. This is placed on the chip. The fins, in effect, increase the surface area of the chip’s top surface, therefore allowing the heat to dissipate to more surface area. This reduces the heat by allowing the heat to spread out over the entire surface area of the heat sink and then allow moving air to remove the heat. The air flow from the fan(s) cools the heat sink down. The larger and more pronounced the fins, the better the cooling will be.

There are two types of heat sinks:

The first is the passive heat sink. This type of heat sink has no moving parts at all, and works simply by providing that extra surface area and allowing the normal air flow to take the heat away. These types of heat sinks are almost never seen on processors today simply because they are not effective enough. You most often see passive heat sinks on things like your motherboards chipset or on your video card processor. 

The other type, most often used on processors, is the active heat sink. It is called active because it has a very obvious moving part - the fan. These units range from somewhat small for some of the older chips, to much larger units used for the newest processors or for heavily overclocked systems. The fans on these units are powered directly off of the motherboard in most cases, using a 3-pin connector. Some are powered from a full-size power supply plug.