Sometimes we forget the power supply when diagnosing a problem with the computer, however, testing the supply first can save you a lot of headaches in finding a solution to your problem. If your computer experiences a blue screen or hangs, shows hard drive error, or just won't boot, it could be a power supply failure. Do these quick checks before you think about replacing expensive pieces of hardware.
Method 1 of 2: Check if it turns on
Step 1. Turn off your computer
Once you've turned off the computer, or if it doesn't turn on directly, press the switch on the back of the power supply. Unplug the source from the electrical power.
Step 2. Open your computer case
Disconnect the power cables from all the components that are inside the box. Follow each of the power cords to verify that everything is disconnected.
Make a note of where everything is connected so you can reassemble the box
Step 3. Create a home essay with a paper clip
You can use a paper clip to help you check the power supply and "trick" it into thinking it is connected. To do this, straighten a paper clip and bend it into a "U" shape.
This clip will act as the pins that are inserted into the power supply in charge of transmitting the “On” signal
Step 4. Find the 20/24 pin connector that normally connects to your computer's motherboard
It is generally the largest connector on the power supply.
Step 5. Find the green pin and the black pin (pins 15 and 16)
What you will need to do is insert the ends of the paperclip into the green pin (there should be only one) and the black pin next to it. Before doing so, look carefully to make sure that the power supply is completely disconnected from the electrical supply, that it is turned off, and that it is not connected to any component of the computer.
The green pin usually appears as the number 15 on the charts showing the pin locations
Step 6. Insert the clip
Once you have located the clip inside each of the pins, place the cable somewhere out of the way. Plug the cord back into the power supply and press the switch on the back.
Step 7. See if the fan is working
Once you have connected it to the power supply you should hear or see the fan start to move. This will allow you to at least check that the power supply works. If the power supply doesn't turn on, recheck the pins (after you've unplugged everything) and try again. If it still does not turn on, the source is most likely bad.
This check will not be able to tell you if the source is working as it should, it will only tell you if it turns on. You will need to run the next test to make sure it is powering the components properly
Method 2 of 2: Check the power output
Step 1. Check the output through some program
If your computer works and you can load the operating system, try using a program to check the power output from the power source. SpeedFan is a free program that will allow you to obtain a diagnosis and will issue a temperature and voltage report. Read the report to make sure the faults are within a certain tolerance level.
If your computer isn't working, skip this step and move on to the next one
Step 2. Turn off your computer
Disconnect the power supply from electrical power. Turn off the source switch located on the rear. Open your computer and disconnect all components from the source. Follow the power cords to make sure each component is unplugged.
Step 3. Test the power supply with a test unit
You can get one online or at a computer store. They are not very expensive. Find the 20/24 pin connector on the source. It is generally the largest wire in the source.
- Connect the test set to the 20/24 pin connector.
- Plug the source back into the power supply and turn it on. Your source should turn on automatically and the test unit should light up.
Some test units require that you turn the source on using a button or switch. Others turn on automatically
- Check the voltages. The 20/24 pin connector will generate multiple readings, but you need to observe 4 essential measurements:
- +3.3 VDC
- +5 VDC
- +12 VDC
- -12 VDC
- Make sure the voltages are within the accepted tolerance level. The values +3.3, +5, +12, can vary +/- 5%. The -12 value may vary +/- 10%. If any of the readings are out of range, the source is bad and you will need to change it.
- Try the other connectors. Once you have verified that the main connector is properly supplying the output power, test the other connection cables one by one. Unplug the source and turn it off between tests.
Step 4. Test the power supply with a multimeter
Straighten a paper clip and fold it into a "U" shape. Find the green pin inside the 20/24 pin connector. Insert the clip into the green pin (pin 15) and into the black pins next to it. This will "trick" the source into thinking that it is connected to the motherboard.
- Reconnect the fountain and turn it on.
- Look for a graph that shows the order of the pins in the source. So you can know what voltage each one has.
- Set your multimeter to the VBDC option. If your multimeter does not distinguish the range automatically, select 10 V.
- Connect the negative probe of the multimeter to the connector pin that goes to ground (black).
- Plug the positive probe into the first pin you want to test. Make a note of the voltage it displays.
- Check the voltages to make sure they all fall within the tolerance threshold. If any of the voltages fall outside the tolerance range, it means your source is bad.
- Repeat the process for each of the peripheral connectors. Look in a graphic that shows the location of the pins, which ones you should test.
Step 5. Reassemble your computer
Once you have tested and verified all the connectors on the source, you can reassemble your computer. Make sure that all the devices are connected correctly and that all the connectors on the motherboard have clicked properly. Once you finish assembling your computer, try turning it back on.