BOOT CAMP 259 (21/01/03)




Back in the mid 1980s, when Amstrad started making IBM ‘clone’ PCs, one of its first models had the mains power supply module built into the monitor. The electronics in the compact desktop box, which didn’t generate much heat, was cooled by natural airflow but a fanless PC was unheard of and there was immediate concern that it would overheat. Many potential buyers were put off by the adverse publicity, Amstrad relented and fitted a fan to the system box, even though it wasn’t needed and didn’t actually do anything, but it solved the problem and everyone was happy.


Today no PC is complete without at least two, and sometimes three or four fans whirring away in the background but these days they’re much more than a customer relation’s exercise. PC power supply units (PSUs) have always had fans, both to dissipate the heat they generate, and to draw cooling air into the PC’s to vent the heat produced by the chips on the motherboard and disc drives. On-chip CPU cooling fans first appeared on the 486 family of processors and they’ve been with us ever since.


Those early pre-Pentium chips used to get quite warm but you could easily fry an egg on the latest generation of super fast processors and some types will destroy themselves within a few seconds if they are not adequately cooled. However, it’s not just the CPUs that need cooling, almost everything inside the modern PC gets hot in the relentless quest for speed and performance every component, from hard disc drives to memory modules and video adaptors are being pushed to the limit and PC cooling has become a hot topic…


Inevitably cooling fans fail so you should recognise the symptoms, and know what to do when it happens. Any change in the sound your PC makes should put you on the alert. Cooling fans rarely just stop, but if for some reason you don’t hear the familiar whirring sounds switch off immediately and have it seen to, as there’s a very real chance of damaging the CPU.


If the fan sound becomes intermittent, or it makes a buzzing noise this may be coming from a wire or cable brushing against the blades of the on-chip cooling fan. Again take this as a warning and switch off immediately. If you are happy to remove the case lid it’s worth having a look (remember to switch off and disconnect the PC from the mains first). Anything fouling the fan should be very gently moved out of the way; if it looks as though it’s going to spring back use a plastic tie-strip to keep it out of the way.


Fans often warn of imminent failure and emit a high-pitched whining noise, indicating a dry or worn bearing. On-chip cooling fans can be quite difficult to replace. They’re usually held in place by a pair of strong spring clips. These may be tricky to get at or obscured by the power supply module and cables.  If you attempt a DIY replacement don’t try to work around the obstructions, remove the PSU and at all costs avoid prying the retaining clips free with a screwdriver. It’s bound to slip and the tip of the screwdriver can fly off and do serious damage to components on the motherboard. If you have the slightest doubts about your abilities consult an expert.


If your CPU fan fails consider replacing it with a more effective design; in any event avoid cheap CPU fans as they have a poor record for reliability. With something as important as CPU cooling it’s always better to have something in reserve so opt for a fan that’s overrated for your processor, or one of the new high-efficiency ‘Flower Cooler’ designs. These have large heat sinks made up of hundreds of separate fins or ‘petals’; they also tend to run a little quieter. Silent or muffled fans are also available if you are troubled by noise but the ultimate in PC temperature control has to be water-cooling or CPU refrigeration. Specialist cooling systems are available for server PCs and they’re popular with ‘overclockers’. 


The fans in power supply modules generally last the life of the PC but they can become less efficient as they get clogged with dust. Loose dust and debris can be sucked out from ventilation slots and the fan grille on the back of your PC with the accessory hose on your vacuum cleaner. PSU fans can be replaced but it’s a job for an engineer, moreover there are many different types and fittings so it is often quicker and easier to swap the whole module. Replacement PSUs are available from most PC dealers and companies like Maplin ( and prices start at around £40.


PC cooling systems become less effective over time and this can have an effect on performance. Some CPU chips, notably Intel Pentium 4 types, have built in temperature control and will automatically reduce their speed when they get hot. Many AMD processors have little or no thermal protection and they can be permanently damaged if they are allowed to overheat. 


The actual temperature at which damage or a slow down in performance occurs varies from make to make. Some CPUs are designed to run at a fairly modest 60 degrees Celsius whilst other perform quite happily up to 90 degrees but rather than waiting for something to go wrong you may be able to take advantage of the fact that many recent motherboards have built in temperature sensors. A simple freeware utility called Motherboard Monitor, available from, displays CPU temperature and fan speed and can be set to automatically sound an alarm and shut the PC down if it exceeds a pre-set limit. Check first that your motherboard is suitable by clicking on the Motherboard List link under ‘Information’ and you’ll also find links to CPU manufacturer’s web sites for details of operating temperatures.


Next week – Portable Data





Central Processor Unit - the main microprocessor chip in a PC



Making a PC run faster by increasing the speed of the CPU beyond its rated design



Very similar to the cooling system in a car with heat drawn from the CPU chip inside liquid filled pipes to a miniature radiator and fan.




As you install more software on your PC changes are made to the Registry, which can slow it down and make it less stable. RegSeeker is a freeware Registry cleaning utility that weeds out unused or unwanted entries. It does much more besides, including displaying Startup information and it allows you to look inside ‘hidden’ history files like Index.dat, which secretly records your Internet activities. The download and more information can be found at:

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