Heat is one of the principal enemies of any electrical equipment, so you should always try to reduce it as much as possible in your system. There are ways of increasing heat dissipation, but they require know-how, money and, on occasions, imagination.
There are fans that allow the rotation speed or the temperature of the dissipater it is in contact with to be controlled, and this is extremely important.
Other devices, which may help a lot when overclocking, are Peltier cells. These curious contraptions are sheets which, when electrical current passes through them, go cold on one side and hot on the other (which still makes it necessary to have a dissipater and fan on this side). These devices are very efficient but also very expensive, they consume a lot of electricity and they are hard to find. Generally speaking, you have to find sites on the Internet (such as www.3dfxcool.com or www.computernerd.com) to get hold of them at a good price along with a range of accessories: heat-conducting resins so that the processor and the dissipater make good contact, fans for graphics cards, fans for the hard disk, etc.
For cooling to be perfect, the best thing is to have one fan that brings cold air in and another to expel it. In a normal machine, the power supply usually gets rid of the hot air, but there is not usually an entry fan, so it would be a good idea to buy a fan and install it in the front part of the computer, where there are normally holes ready to take an 8x8 cm fan.
In any case, there are two things you should not forget: 1) hot air rises, so the air vent should be up high (NEVER below the cold air vent); 2) there are few ventilation systems as effective and as cheap as opening the computer casing. It doesn’t look very pretty (although this is just a matter of taste) but it does work very well.
You should remember that by increasing the frequency of the clock you also increase energy consumption, and that by adding fans we may be exceeding the power supply limit .
1 What is overclocking?