How to Check Power Supply on PC

A PC’s power supply can play an integral role when it comes to diagnosing computer issues. Instead of embarking on multiple troubleshooting tests, it’s always wise to start by checking the power supply. Whether it’s down to hard drive errors, constant crashing, or an inability to start up, the power supply might be the cause of the problem. So, how does one go about checking the power supply on a PC?

Shut Down the PC

First thing’s first, the PC needs to be tested to see if it powers on. Therefore, shutting down the PC is a good place to start. If it isn’t starting up at all, the switch on the back of the power supply should be flipped before the power supply is unplugged from the outlet.

Open the PC Case

The next port of call is to open up the computer case and disconnect all power supply cables from the integral components. This is a careful process and each cable should be followed to ensure each component is unplugged correctly. It’s a good idea to note down where each cable was inserted for ease of reassembly later on.

Make a Paperclip Tester

A paperclip is a simple way of testing the power supply as the PSU can be tricked into thinking it has been turned on. For this to be successful, a paperclip needs to be straightened before it’s bent into a U shape. The paperclip can then be placed in the power supply to give the “power on” signal.

Find the 20/24 Pin Connector that Usually Connects to the Motherboard

This is easy to locate as it tends to be the biggest attachment of any power supply.

Locate the Green Pin and a Black Pin

Typically speaking, there will be one green pin that will indicate where the paperclip needs to be inserted. This is because the paperclip’s ends need to be inserted into the green pin and the neighbouring black pin. However, the power supply must be fully disconnected from the power outlet before doing this. Similarly, the power outlet should be turned off and disconnected from other computer components. Usually, the green pin will be pin 15 on a pin chart.

Slot the Paperclip in Place 

Upon the insertion of the paperclip, the cable needs to be placed in an area where it won’t be disrupted. Then, the power supply can be plugged back into the outlet, and the switch can be flipped back on.

Inspect the Fan

If the power supply obtains energy, the fan will begin to move. If the fan does not start working, everything should be disconnected, and the paperclip process should be repeated. The power supply is likely faulty if the fan still doesn’t work. Although this process dictates whether the power supply is switching on, it won’t ensure its outputting correctly. For this reason, the following steps also need to be taken.

Use Software to Assess the Output

If the PC is functioning and the operating system is loading, the software can be used to check the output of your power supply. To read the PC’s diagnostics and report any voltages and temperatures, a programme called SpeedFan can be installed on the machine. These readouts can then be assessed to see if they adhere to accepted tolerances. This step can only be followed if the PC is working; if it’s not, continue to the next stage.

Close Down the PC

The power supply must be unplugged from the outlet when shutting down the PC. Next, the power button on the rear should be turned off before the computer is opened and all components are disconnected. Once again, each cable should be followed from the power supply to guarantee each component is properly disconnected.

Use a Power Testing Supply Unit to Assess the Power Supply

To use a power supply unit, it first needs to be connected to the 20/24 pin connector. Next, the power supply should be plugged into the outlet and switched on, which should automatically switch on, lighting the power supply tester up. Despite this, some power supply testers need to be turned on via a button or switch, whereas others will automatically switch on.

Following this, the voltages need to be checked; amongst the multiple readouts, the four key measurements are +3.3 VDC, +5 VDC, +12 VDC, and -12 VDC. These will need to be assessed to see if they sit within accepted tolerances. For +3.3, +5, and +12, they can be within +/- 5%. However, the -12 can be within +/- 10%. Anything outside of this indicates a poor power supply that requires switching out. Once this has been determined, the other connectors should be tested one at a time, turning off the power supply after every test.

Use a Multimeter to Assess the Power Supply

The process with the paperclip should be repeated before plugging the power supply back in and turning it on. Next, a pinout chart will need to be located as they indicate which pins provide which voltages. The multimeter should be set to the VBDC setting and, if it doesn’t auto-range, set the range to 10V. Then, the negative probe should be connected to the black pin, and the positive pin should be connected to the pin that needs to be tested.

It’s always a good idea to note down these displayed voltages. If any of these voltages sit outside the tolerance range, you can be sure that the power supply is faulty. This process should be repeated for every peripheral connector.

Reassemble the PC

The final step is to reassemble the PC, ensuring that everything is properly seated and plugged in.

Check Power Supply with Ideal Power

Here at Ideal Power, we’re experts in power conversion. Please don’t hesitate to get in touch for further guidance regarding power supplies.