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Computer Power Supply Unit (PSU) Problems

The power supply unit (PSU) is the component that gives power to the various components in your computer. Hence when your computer power supply has a problem, this can unfortunately lead to major problems.

There are a few different symptoms/problems which are caused by computer power supply problems. As a result, this guide has been written to outline the five main symptoms which usually indicate a problem with your power supply. We then outline some possible solutions to help with your computer power supply troubleshooting. As a pre-emptive warning though, be warned that the majority of PSU problems can only be fixed by buying a new PSU and replacing the old one.

Symptom 1 - Computer is hot to touch, or you smell burning

Power supply unit

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Whilst scary, this is usually a problem with the PSU fan (and not the PSU itself). Thus we would suggest that you try to clean the fan (since it can get clogged up with dust) and the area around it. If this still doesn't work and the issues persist, then it probably is a fault with the power supply unit itself. In this case, you'll need to purchase a new PSU and replace the old one.

To clean the PSU fan, either use a PC vacuum or compressed air (as long as the compressed air is designed for cleaning computer components, that is; be sure to check its labels first). You might need to open your computer's case to get access to the PSU fan. Warning: be sure to turn off your computer and fully unplug it before doing this.

Symptom 2 - Whining/grinding noises when turning system on or off

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This is thankfully almost always an issue with the PSU fan and not the unit itself. These noises are usually caused by dust clogging up the power supply unit fan and thus preventing the it from turning/functioning like it's supposed to. Hence use the PSU fan cleaning tips (second paragraph of symptom 1 above) to clean the fan and hopefully this will solve the noice issues.

Symptom 3 - Computer turns off or restarts, or won't turn on at all

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If this isn't caused by a software or operating system issue (see Problem 3 of our computer problem checklist article), then this might be because your PSU is being overloaded - in other words, your computer's components might be consuming more power than the PSU can provide. This is probably the case if you recently upgraded a component in your computer. If you didn't do this, then this suggests your PSU is failing.

Either way, you will need to get a new PSU. If you did recently upgrade your computer - in other words, your current PSU is overloaded - then consider getting a better quality and/or higher wattage power supply unit. If this is due to a failing PSU, simply purchasing a new, similar unit should solve the problem.

Symptom 4 - Not all computer components start up at same time

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The way a power supply unit works is that it provides different power to different components (via various rails). If - when turning on your computer - you hear or notice that some components are starting up after other components, this might suggest that either the unit is overloaded or it is failing (see symptom 4 above for details about how a PSU might be overloaded).

To resolve this, you will need to replace the unit, possibly with a higher quality and/or higher wattage PSU.

Symptom 5 - PSU fan not working nor blowing very hard

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Firstly, try cleaning the fan using the PSU fan cleaning tips in symptom 1 above. Be sure to turn off your computer and unplug it before performing this step. If after cleaning it you notice that the unit's fans still aren't working/blowing correctly, this would suggest that the power supply unit is broken and thus you will need to replace it.