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How to Test a Motherboard With a Multimeter

Most people would agree that the motherboard is the most crucial part of any computer. It contains an intricate circuit that controls all the necessary functions of a system. If the motherboard gets faulty, there goes your device. However, there are ways to check the integrity of the motherboard if you notice a fault developing. Based on your results, you may be able to diagnose the fault and fix it in time.

A multimeter is a simple tool that can help you check basic voltage and resistance in a motherboard. Also called a volt/ohm meter, this tool can measure voltage, resistance, and current. Without searching too far, it’s easy to see why a multimeter is useful when troubleshooting a motherboard. With multimeter readings, you can check if there is a short or open circuit, or enough voltage supply to the motherboard. These are typical issues that can occur on any motherboard.

Is Testing a Motherboard Necessary?

Carrying out routine health checks on your motherboard is crucial for optimal performance. Firstly, check for signs of physical damage like cracks, wear, and loose parts. Also, look for rust or corrosion, which could indicate serious wear and tear. However, do a multimeter check if all these are in place and you’re still experiencing these faults:

●  Overheating

●  Blue screen of death

●  Failure of the device to start

●  Freezing

●  Random crashing or shutdown

One or more of these symptoms could indicate poor motherboard health. In this case, it becomes necessary to do a multimeter check and start ruling out different possibilities.

Testing a Motherboard With a Multimeter

Motherboard Testing With a Multimeter

With a multimeter, you can check either of two factors on your motherboard: voltage or resistance. If your device shows signs of a faulty motherboard, the power connector may not be supplying the correct voltage. In this case, use the multimeter to test for voltage. Alternatively, there may be a short or open circuit in the motherboard, and a resistance test can find that out.

Voltage Test With Multimeter

1. Connect Your Device to a Power Supply

First, ensure your device is connected to a power supply because there needs to be a current to test voltage. Locate the 20-pin ATX connection and insert.

2. Set the Multimeter Voltage and Probe

For reliable readings, configure the multimeter to 20V DC. Probe the backside of the ATC connector using the black multimeter probe. Probe the lead in pins 15, 16, or 17, which are the GND pins, and alternate to check them. Use a 20-pin ATX chart to locate the pins if necessary.

3. Set the Red Probe

Using the red probe, test pins 9 (purple, VSB) and 14 (green, PS On) and observe the values. You may then press the power switch and see if the value drops. Afterward, test pin 8 (gray, Power OK) with the red probe and observe. Also, hit the power switch and watch for a drop in value.

4. Study Your Results

Pin 9 should read a value of 5V, while pin 14 should read between 3 – 5V. If the values deviate, there may be an issue with the PSU, causing the motherboard to fail. When you reset the power switch, the number should drop to 0 and rise back to normal on pin 14. If this fails to happen, the motherboard may be defective.

Pin 8 should read a value above 2.5V, the amount of voltage the computer needs to start. It means that your computer is good to start up. When you hit the power switch, the value should drop to 0 and rise again.

Resistance Test With Multimeter

1. Disconnect All Power Supply

A resistance test does not require power running through the device. Thus, disconnect the computer from the power supply and let all charge drain. Ascertain that every charge drains by waiting a short while.

Testing a Motherboard With a Multimeter

2. Set Your Multimeter

Set the multimeter to the lowest setting at 200 Ohms. Touch the probe’s two leads together to reset the meter. You may also touch both leads to the computer’s chassis, and you should get a zero read. This is to ensure that the probes calibrate accurately.

3. Remove the ATX Connector

Detach the ATX connector from the motherboard. The ATX supplies power to the motherboard through the PSU. Expose the PSU pins by disconnecting the power connector from it.

4. Test the Connector

Carry out the first test on the connector to determine how much resistance they have. While testing the colored wire pins on the D/C connector with the red probe, leave the black lead on the computer’s metal chassis. A reading of 50 or higher should be produced by each colored wire. Any reading below this means that the power connector needs to be changed.

Next, test the black wires with the red probe on the A/C connector while maintaining the black lead on the metal. The black wires are ground connectors; thus, they should all give a zero reading. Any value other than zero could mean a short in the motherboard.

5. Test the PSU Pins

You may perform further tests on the PSU pins to verify your results or if all the wire connectors test well. Refer to the ATX-20 pin chart for this test if necessary. To inspect the GND pins, remove the CPU from the motherboard socket. Test all ground pins, including 3, 5, 7, 13, 15, 16, and 17, using the red probe while maintaining the black lead on the metal. The reading from each pin should be zero. Any other value may indicate a bad connector or a short circuit.

Final Thoughts

A motherboard can develop a variety of faults over time. Random shutdowns or reboots, overheating, freezing, or the blue screen of death could be signs of a faulty motherboard. You may need to run a few tests with a multimeter to confirm your diagnosis. A multimeter is a handy tool that can read the voltage and resistance with your power connector and PSU. A multimeter test on a motherboard can either be a voltage or resistance test.

A voltage test will determine whether the power connector is providing the motherboard with the ideal voltage. If it isn’t, the motherboard can develop various faults. However, changing the power connector may help solve the problem. Meanwhile, a resistance test will check if there are any short or open circuits within the motherboard. A short might have resulted from a power surge, and a multimeter can pick up such faults. This may mean a complete replacement of the motherboard. Based on the results of your readings for either test, it becomes easier to diagnose the problem with your motherboard. Remember that these tests are easy to carry out at home, but further diagnosis may require the help of a professional.