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How to Test a Motherboard with a Multimeter (Guide)

A motherboard is an essential component of a laptop or desktop computer. Many issues with the motherboard such as incorrect airflow can harm a lot of sensitive circuits. It can lead to temperature problems or insufficient voltage. A basic multimeter may test various issues with a motherboard. If your trying to diagnose any issues knowing how to check a motherboard with a multimeter is essential.

In general, testing a motherboard with a multimeter is quite simple. First, disconnect the power supply and make sure that there is no residual electricity. After that, set your multimeter to the lowest resistance option. Ensure that the meter reads zero before examining the motherboard. Connect the computer to an alternating current power supply via the 20-Pin ATX connection. Then, connect the black and red lead to the chassis and PSU’s AC ground pin. A reading of zero indicates that everything is fine.

Let’s explore further and learn how to check the motherboard with a multimeter. For the basic use of a multimeter, you may click here.

2 Ways to Test Motherboard with a Multimeter

multimeter and motherboard

There are typically two reasons to test a motherboard: a voltage/power supply disturbance or short circuits on the motherboard power. (1)

#1. Voltage Test

Do the following steps to test motherboard voltage.

Step 1: Check that the inserted 20-pin ATX connection in the computer is on. Set the multimeter to 20 volts of DC. Test the rear of the connection with the black multimeter probe, making contact with the GND pins–15, 16, or 17.

20-pin ATX connection

Step 2: You can use the red probe to test the following pins. Pin 9 (Purple, VSB) should be at 5 V (any other reading indicates an issue with the PSU). Pin 14 (Green, PS On) will be between 3 and 5 volts. When you turn off your computer, the PS On value should be zero. Other readings suggest a bad switch.

Step 3: Check Pin 8 (gray, Power OK) with the red probe; it should be above 2.5 V, indicating that the computer can start. When you press the reset button, the Power OK reading should decrease to 0 and climb up.

#2. Short Circuit Test

Short circuits might cause the motherboard to fail and might damage other components and the motherboard. Checking your motherboard for short circuits can be great for preventing future issues.

The following steps will help you test the motherboard.

Step 1: Disconnect the computer from the power supply and wait a few minutes for any extra charge to drop. Set the multimeter to the lowest Ohm level (about 200) and touch the probe leads together to zero the meter. When you add the two leads to the metal surfaces of the computer’s frame, the zero reading must be the same. (2)

power supply and multimeter

Step 2: Remove the ATX connector from the motherboard with care. Maintain the black probe on the frame’s metal and use the red lead to check the A/C ground pin on the PSU. Check on the black wire pins as well that are on the D/C connection. The result should all be zero.

Step 3: Maintain the black lead on the motherboard while using the red probe. This is to test the values of the colored wire pins on the D/C connection. All colored wires should have a reading of at least 50.

Step 4: Take the CPU out of the motherboard socket. Refer to the PINs on the board’s connection using the ATX 20-pin chart. Keep the black line attached to the frame and use the red lead to test the GND pins on the motherboard cord. Pins 3, 5, 7, 13, 15, 16, and 17 should return a zero reading. Any other reading suggests a lousy connection.

Things to Remember

Before doing a motherboard test on a laptop, you should test the power adapter. The actual cause of the laptop not turning on might be the charger, which is failing to deliver the required electricity.

Wrapping Up

A malfunctioning motherboard exhibits symptoms such as blue screen errors. The signs point to a problem with the motherboard or another piece of hardware. That is why it is ideal to know how to check the motherboard with a multimeter.

The multimeter test can disclose whether or not the motherboard power is faulty. By identifying the error, you can diagnose fix the motherboard. Otherwise, a replacement is a final option.

For all the multimeter articles, check this link. Until our next article!

(1) motherboard – https://study.com/academy/lesson/what-is-a-motherboard-definition-function-diagram.html
(2) metal surfaces – https://pubs.rsc.org/en/content/articlelanding/

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About Sam Orlovsky

AvatarCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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