You may have experienced your computer intermittently re-booting for no apparent reason. This can be annoying, and can mean you have lost valuable work that you we in the process of creating.

If this has happened once, then your chances of explaining the cause are remote in the extreme. If you find it happening regularly, then it is clearly in your interest to find and fix the problem.

There may be a simple explanation. With most modern computers, the system comes with built in circuitry to monitor the state of the computer. One of the checks built into your system include testing the power supply levels. The power supply is not a component most people expect to fail. Most are concerned that their disk drives will be the major cause of failures. The fact is power supply problems are relatively common.

The power supply communicates to the motherboard with a (power good) signal. This will happen if the power output is within specification. If the power good signal is not present, the computer will simply not start up. Seems simple enough, however things do not always fit into the good or not good categories. When you have a power supply that is failing, its outputs can fluctuate. The computer may boot up correctly a little later the power supply falls out of range. The computer will detect this and activate the reset logic. The reset logic shuts the machine down, this relieves the load on the power supply, and it then supports a re-boot. It is the same as if you pushed the reset button yourself, it appears to you as a random re-boot.

To test the power outputs, you really need access to a multi-meter. You should have experience in using one. This might be something you may prefer to leave to an experienced technician. Alternatively, you can try replacing the power supply with a spare that you know to be working. If this corrects the intermittent re-boot, then you have solved the problem.

When replacing a power supply, select a known brand, and I suggest you choose one that is rated to at least 400 watts. This, of course, depends on what load your computer is supporting. Upgrading to a faster processor, installing additional or faster disk drives, or adding other devices will all add to your computer’s power requirements.

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You may have experienced having your computer intermittently hangs-up, or may re-boot itself for no apparent reason. This can be annoying, and can mean you have lost valuable work that you we in the process of creating.

If this has happened once, then your chances of explaining the cause are remote in the extreme. If you find it happening regularly, then it is clearly in your interest to find and fix the problem.
There are a few things you can check for yourself that may save you a trip to the repair shop.
 
With most modern computers, the system comes with built in circuitry to monitor the state of the computer. One of the checks built into your system is to test the operating temperature. The computer may shut down if this moves outside the desirable operating range.
 
For your system to run at the correct operating temperature it is important that air circulates freely in and around the case. If you have the computer case installed inside an enclosure, then this may be the first thing to consider changing. Similarly, I have seen computers covered with books, manuals and paper documents. These again can hinder air circulation, and these items should be removed. Take a look at the slotted vents in the sides of the case. These slots can become blocked by an accumulation of dust. Because the computer is usually always drawing some power, it has a constant electrostatic charge. A computer is second only to a vacuum cleaner in its ability to suck in dust and fluff.

Taking the cover of the case will also show the dust build-up inside the computer. Be careful removing dust accumulations from internal components. This is probably best done with a soft artist’s brush or an aerosol can of compressed air.

Next, take a look at the internal cooling fans. Modern computer usually have a cooling fan perched on top of the processor. This fan should be clear of dust, and running freely, without obvious scraping noises, when the computer is operating. It is OK to start the computer with the case cover removed, just be careful not to poke things into the various components. There will also be a cooling fan inside or attached to the power supply. This again should be free of dust and running freely. Some computers may also have an additional case fan. This will be screwed on over one of the slotted case vents, and typically be running from a cable connected to the mother board. Not all machines have a separate case fan, but if it is there, it is there for a reason. Apply the same checks to this fan.

If you have identified faults with your cooling fans, this may require a trip to your local repair shop. The repair technician may also suggest that the CPU heat sink be removed and re-placed with fresh heat transfer compound, which is a straightforward job for an experienced repairer.