The computer power supply unit (PSU) is one of the biggest pieces of hardware that directly affects user performance. An adequate power supply is a must for systems to run seamlessly, and many problems occur if the power supply unit fails to provide sufficient voltage levels. For many problems, checking the power supply can bring out the solutions very easily. In this article, we’re going to discuss how to test the computer power supply with multiple methods.
What is the PSU of a Computer?
To test the computer power supply, we must learn about itself. PSU (Power supply unit) is the main unit through which electrical power is delivered to the CPU of a computer and then distributed. It converts AC power from household inlets and then converts them to DC power as needed for computer components to run effectively.
The power supply unit consists of some regular electric components like a transformer to increase or reduce voltage level, a rectifier that converts AC into DC voltage, voltage regulators to control the output voltage as needed. In the outside of the PSU, we can see a fan that acts as a cooler for the CPU and PSU, a wall-socket connection, and most importantly, a 20-pin or 24-pin connectors to attach the PSU with the motherboard.
20-Pin and 24-Pin Connector
Before starting the procedures, it’s better to have an idea of 20-pin or 24-pin connectors, as the testing process depends on it. The 20/24 pin connector supplies power from the PSU to the motherboard components like processor, memory, and other parts directly. Inside the connector, we can see wires with multiple colors.
The black connectors work as a ground unit.
The gray connector is essentially a voltage level checker, that determines if the voltage is adequate.
There are red, blue, orange connectors for voltage supply. These supply 5V, 12V, and 3.3V respectively, both positive and negative.
The green connector is the main ON connection. There is only 1 green pin located at pin 15.
If, however, the wires are colored the same, there’s an easy way to locate the green pin. Take the connector while facing the connecting clip towards your face. The green pin is the 4th pin from the right side.
How to Test Computer Power Supply
Testing disk speed, power supply, or other units of a PC is great for clearing out issues and make room for improvements. There are two basic methods to check if the computer power supply is working correctly.
- Check if PSU turns on or not (with a paper clip)
- Check the individual pins (with a testing unit like multimeter)
Checking if PSU Powers On
This is an easy way to identify if the power supply turns on or not. However, we can’t check if it’s working correctly, and to do that we need a multimeter.
To check, we need a paper clip. If the clip is coated with paint, we have to remove paint from the two ends of the clip, and the metal portion will come out. Before doing these operations, we should ground ourselves to prevent any unwanted electrical surges that can damage the components.
- Firstly, we shut down the computer and disconnect power from the wall socket by removing the plug.
- Open the CPU back cover to expose the power supply.
- Unplug the PSU connector from the motherboard. Then disconnect the power supply unit from the CPU by removing the screws.
- Take the 20-pin or 24-pin connector. Notice that there is 1 green pin, some red, blue and black pins. The green pin is usually located at pin 15.
- Take the paper clip, and insert one end into the green pin, and the other end to any black pin. (Make sure the PSU is disconnected from the socket before doing this).
- After inserting, place the 20/24 pin connector undisturbed.
- Plugin the power socket and turn on the power connection.
At this point, the fan should rotate. If it doesn’t, then most likely your power supply unit is dead. If it rotates, we can proceed to the next step.
Checking the Power Outlet
If the PSU turns on in the previous test, that means it isn’t dead. Now we have to check if all the connectors are working properly. For this, we need a multimeter. These are relatively cheap hardware found in most electric stores. Multimeters usually have a black probe and a red probe. There is a knob to switch between AC and DC connections.
With the multimeter, we first check the power outlet. Notice that the outlet has a neutral (N), a live (L) slot at the bottom, and the 3rd one is ground. Next, we rotate the knob to AC connection (V with a wave sign). Now we place the black probe in neutral (N) and red probe into the live (L) slot and turn on the power.
We should see a reading somewhere between 230-245V which varies with the rated voltage of individual countries. If the reading matches the rated voltage of your zone, then the power outlet is ok.
Checking the Individual Pins
Take the 20/24 connector with the paper clip inserted into a green and a black pin. Now we have to check if all the pins are giving the voltage as rated in the chart before. To do this, switch the knob of multimeter to DC connection (V with a straight line).
At first, insert the black probe into the black pin-24 which is the furthermost. Then attach the red probe to the next red pin-23. The rated voltage here is +5V, so we should see around 5V on the multimeter with a 4% tolerance on value (4.8 to 5.2V).
The black probe stays in the same place, and we have to try different pins for the red probes. Skip the other black and grey pins, then insert the red probe in each pin one by one and notice the readings. The readings on the multimeter should be close to the values given in the chart. The red pins would give +5V, blues give -12V, oranges give +3.3V, and whites give -5V and so on.
Check one side of the connector lane, then swap to the other side while placing the black probe to another black pin, and repeat the process again.
By checking the individual pins, we can see how much voltage each one gives. The voltages should be close to the original values. If so, then the power supply unit is completely okay. If any pin gives more or less than the acceptable values (maximum 4% tolerance), we can identify that pin and fix them from any professionals.
Identifying Problems Caused by PSU Failure
PSU failure can cause a lot of problems. A majorly damaged power supply would fail to boot the computer at all. Damaged pins can supply excess voltages to the components that can cause the components to damage or even burn out.
The cooling fans associated with the power supply can stop cooling effectively, which can increase CPU temperature to a dangerous level. Minor problems associated with the PSU are, blue screens of death (BSoD), frequent computer crashing, storage failure, unable to launch apps, hard drive reading errors, and other common problems. If these problems occur frequently, it is best to check the power supply at first. We can also use 3rd party apps like SpeedFan that checks if fans or other hardware are working correctly.
In this article, we’ve briefly discussed some easy ways on how to test the computer power supply. Damaged power supply units can cause great deals of further damage to your computer if ignored. So, it is best to check if this is working correctly at the first sign of trouble so that you can identify the problem, minimize the damage, and the cost to fix them.