The laws of thermodynamics spell out the fate of your computer. Waste energy manifests itself as heat, the random movement of molecules. Some random events are a bit more extreme than others and result in the microscopic circuits separating or burning through. At that point your computer becomes little more than an interesting piece of shiny silicon suitable for a key chain fob. Most of the time heat manifests as semi-random lockups and failures, typically when the machine is needed most.
It should be obvious by now that heat and temperature aren’t as simple as they may seem. There are many sources of heat in your system. Once you know the cause and effects of heat in your system, you can go about eliminating it as a problem. Here’s what you need to know.
Core temperature
Core temperature is the temperature of the device (e.g., processor or hard drive) as measured on the inside. As such, core temperature is the critical factor. All of the temperature control devices inside your system are there to minimise core temperatures. There's no need to install additional cooling if your core temperatures are acceptable.
Measuring core temperatures can be problematic, since external thermometers read only the surface temperature of the circuit. While there may be only a few millimetres of intervening material, with modern circuitry being measured in microns, these miniscule millimetres might as well be miles. Most processors are now equipped with a thermal diode that measures the temperature within the circuitry itself.
Different processors from even the same line can have widely varying acceptable core temperatures. Typical core temperatures are listed below along with the location of the manufacturer’s online records. Intel has not published an official maximum core temperature for Pentium IV processors due to the on-board thermal shutoff system. Other processor core temperatures are as follows:
- Pentium III: 75-90 C
- Pentium IV: 80 C (as indicated by developer data on Intel’s Web site)
- AMD Duron: 70-100 C
- AMD Athlon: 70-100 C
- AMD Athlon MP/XP: 85-95 C
Devices other than processors can suffer from heat. For example, hard drives and memory occasionally suffer. Unfortunately, there's little way to measure their core temperatures, which forces you to examine their environment.
Ambient temperature
Many people believe that ambient temperature is the temperature of their office, but in relation to a processor or video card ambient temperature refers to the interior of the case. Some motherboards have sensors that can monitor the case's interior temperature, but if your computer doesn’t have this feature, a $5 digital indoor/outdoor thermometer with a sensor on a cord and a high/low memory will work as well. In general, case temperatures should be kept below 80 C.
Ambient temperatures are controlled with case fans. Proper fan design generally has an air-intake fan at the front of the case at the bottom with a rear exhaust fan near the top and as close to your processor as possible. This lets natural convection work in your favour as the warmed air rises. Accidentally reversing a case fan can significantly alter the case's ambient temperature, especially when high-flow fans are in play.
