Here's what to do if your PC's cooling fan has suddenly become a lot louder.

QUESTION I have a one-year-old Packard Bell desktop PC with a Pentium dual-core CPU and 3GB of RAM. If I have only one web page open and nothing else, CPU usage fluctuates between 0- and 5 percent. The fan is on, but it's very slow and quiet. I trade foreign exchange during the week and have two platforms open; during busy hours the CPU usage can be between 50- and 75 percent, and the fan is on constantly, spinning very fast and loudly. I close down all other applications to reduce the load on the processor, but there are still lots of processes using a small percentage of the CPU. I'm worried about the machine overheating. If I were to upgrade the PC, should I be looking for more RAM, a larger hard drive or a faster CPU? Bturner

HELPROOM ANSWER It's normal for your CPU fan to increase in speed and volume when the PC is under load. It's probably no cause for concern unless this has started to happen only recently. If the PC used to be much quieter and is getting progressively louder, you may find that a significant amount of dust has built up inside the machine over time, causing the fan to have to work much harder to force cooling air through the system.

Check any vents and fans visible from the outside for dust. If you're confident about looking inside your PC, then you should also remove the case door and check the CPU cooler and fan. A can of compressed air can help clean out any inaccessible areas. Do make sure that the PC is switched off when you do this, since these cans can often spray out a little liquid propellant along with the compressed air. This will evaporate very quickly, but you don't want it making contact with any live components.

What's more important than the fan speed is the temperature of your PC's internal components – the processor in particular. You can use a software application to monitor the temperature sensors on your PC's motherboard, such as CoreTemp (free download).

This will provide you with a wealth of system information, as well as real-time temperature readouts. You can find the safe operating temperatures for your processor by searching Typically, CPUs can handle running at around 60 percent C.

If your processor temperature is within safe limits, but the level of fan noise is uncomfortably high, you may like to consider replacing the CPU cooler with a third-party model. You can usually find quieter and more efficient coolers than the one supplied with your PC, but there may be physical constraints on which coolers can be installed – some enthusiast coolers are very large indeed.

Another option is to install some adhesive sound-absorbing material inside your PC case. Quiet CPU coolers, sound-absorbing material and compressed air dusters can be purchased from many outlets, including

If you have a laptop or all-in-one PC we wouldn't recommend opening the case, especially if your PC is still under warranty. Try blowing out some dust from the vents, and if the situation doesn't improve you may need to have it professionally serviced.

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