How to stop a computer from melting

The hows and whys of cooling computers.

Disclaimer: As ever, usual disclaimers apply here. If you take your PC apart, then make sure you know what you are doing. I can't be held responsible for anyone modifying their PCs. I am merely putting this information on the web, to show what is possible. Experiment at your own risk.

Heat and computers don't mix that well. This was a lesson I first learnt back in 1985, when I tried to modify my Sinclair QL. If you see a heatsink, it is generally there to remove heat, and taking off the heatsink, can:

  1. (a) Really mess up your computer's performance.
  2. (b) Burn your fingers.

If you are trying to eke every last ounce of performance out of a high end PC, you may want to pay attention to cooling, especially if you are using add-in cards such as 3-D graphics accelerator cards or overclocking your CPU. They run hot. If your system freezes, then you may want to turn down the speed of the 3-D accelerator card or the CPU, or add in a cooling system.

PC Cooling Systems

PC cooling systems have come a long way from a simple thumbnail sized metal plate heat sink, nowadays, with the considerable heat produced from a CPU, there are a wide range of innovative cooling solutions. Examples of these include:

Cooling systems can be as simple as extra fans, or more advanced alternatives such as combined Peltier effect devices/fans or heat exchangers. You don't really need to bolt an industrial sized refridgeration unit on your machine unless you are trying to run a 450 MHz machine at some clock frequency in the Gigahertz range.

Alternatively, you can do it for the same reason as I did it....a combination of scientific curiosity and because it can be done

Astronomy CCD Cooling Systems

A good source of a dataset on using active cooling systems such as Peltier effect devices and heat exchangers, is the amateur astronomy community. The amateur astronomers have been using CCD's to view the stars for years, and have developed some imaginative and sophisticated methods of cooling their CCD chips.

With a CCD attached to a telescope, the goal is to minimise thermal noise, and thus gain a better image of the astronomical object being viewed. To minimise the thermal noise, the CCD can be actively cooled by means of a Peltier effect device and a fan. It is possible to get performance gains even from modest PC webcams used for astronomical imaging by using a Peltier effect device and a fan to cool the webcam imaging system.

Try the following web sites for information on cooling methods used in amateur astronomy:


The conventional way to cool a PC (especially the CPU), is to use a combination of heat sinks and fans. Essentially, you remove the heat from the heat sink through the fan, faster than it can build up to an amount to stop the PC from overheating.

Point 1. - Use a decent CPU cooler

Don't try and save money on the CPU cooler. In a PC, with components such as motherboards and CPUs which are not cheap, then it is a false economy to save money on the cooler, if it is not up to the job and causes the motherboard or CPU to fry. Don't pick a cooler on the basis of which one has the coolest anodising.

Pick it on the volume of air it is capable of moving (sometimes referred to as CFM or Cubic Feet per Minute). One of my previous PCs used a CPU cooler called the Swiftech MC-462A. It wasn't cheap, it looked like a miniature fusion power station, but it was very good at doing what its supposed to do, i.e. cool the CPU. One just needed to be prepared to wear headphones when it was turned on. It was annoyingly loud. I downsized my PCs to small form factor PCs, which used less power, and as a consequence, was able to make use of the Shuttle technologies heatpipe system, which cleverly uses heat pipes to draw heat out to the back of the PC case, where a large fan uses convection to remove the heat.

Point 2. - Don't ditch the case

Running a PC without its case is not neccessarily a good idea. The case provides an efficient way of moving hot air out of the system. Without the case and case fan, the system relies on convective cooling using the CPU fan alone, and believe me, it just doesn't cut the mustard. You need a decent flow path to move fresh air through the machine to keep the temperature down.

Point 3. - You can never have enough fans

Fans are good. They can be noisy though. The basic rule of thumb is, the more fans, the better, since they provide more airflow, and hence more cooling. Nowadays, most PCs come with a minimum of a power supply/case fan, and a CPU fan. Normally in every day use, these are sufficient for cooling a computer. The overheating isssues start to crop up when you overclock your CPU, or add in 3-D graphics accelerator cards, or overclock 3-D graphics accelerator cards. Then, additional case fans become important, in order to move sufficent air through the case to cool everything.

In order to reduce any noise produced by fans, there are a few steps you can take; (1) choose low noise fans to start off with a low noise level, (2) use rubber fittings to attach the fan. This reduces virbation and in turn reduces the noise produced.

BTW, if you ever hear anything rattling in an alarming manner when you switch a PC on, it is often a dodgy case fan or CPU fan. Sometimes, thumping it will cure the problem..