How Test Motherboard Without CPU

How To Test A Motherboard Without A CPU (Can You?)

The motherboard is the heart of the PC, and all components in the PC connect to it for power. If the motherboard fails to work properly, the connected components will also fail to work as intended. But, how will you know it’s a motherboard problem that is causing system failure. The only way to know whether the motherboard is the cause of the problems is to test it. But can you test a motherboard without a CPU? The below guide provides you with everything you need to test a motherboard with no CPU.

Are you looking for a quick and reliable solution? Yes, you sure CAN test a motherboard without a CPU. With the Kaisi Professional Precision Magnetic Screwdriver, disassemble the PC and remove the motherboard from the casing. Then, use the highly rated AstroAI Ohm Volt Amp Tester Multimeter to test the motherboard for any issues.

Can You Test A Motherboard Without A CPU

Yes, it’s possible to test a motherboard without a CPU by plugging in the cables and the correct RAM. Then, try to boot up the system. Of course, you won’t see anything on the monitor, and so there is no need to connect the display. However, you will hear some noise produced by the fans as they spin. 

Also, you can see the fans rotating once you power the motherboard up. In case you have linked the motherboard into an internal speaker or the motherboard comes with a built-in one, you may hear some beeping sound that tries to warn you that the motherboard is working correctly but there is no CPU detected. 

However, some motherboards may fail to produce this beeping sound even when they are working correctly, especially those with LED indicator lights that light up when they can’t detect a CPU.

Testing Motherboard Without CPU: How To

Now that you have seen it’s possible to test a motherboard without a CPU, let us dive into how to do it. 

Power-On Self-Test

One thing you may need to keep in mind is that most motherboards don’t go beyond the Power-On Self-Test (POST). However, some of the advanced modern motherboards can get past this point and do BIOS upgrades even without a CPU. Regardless of the make and features of the motherboards, all allow you to test some of the onboard functionalities. 

For instance, the LED lights in motherboards light up when you switch them on even without a CPU. The cooling fans start spinning, which indicates the motherboard is in operation. 

However, the spinning fans and lit LED lights only indicate the cooling and lighting functions of the motherboard are working properly, but that doesn’t mean other components and functionalities are working as they should be. 

That brings uncertainties, because the motherboard may fail to function even after assembling the PC. These uncertainties make this testing method somehow unreliable.

Onboard Speaker

If your motherboard comes with internal speakers, you may hear a series of beeping sounds from the motherboard once you connect and power it on. In case the motherboard doesn’t come with internal speakers, you can connect it to external speakers. 

The beeping sequence is commonly known as beeping code. The beep codes generally indicate that the motherboard is trying to establish a connection with the CPU. Also, the motherboard may produce these being codes if you power it on without RAM. 

Although beep codes are a sign of a properly working motherboard, failure to hear the beep codes doesn’t mean the motherboard is not working properly.


The multimeter is one reliable tool that you can use to test a motherboard whether it’s working properly or not. The advantage of a multimeter is its ability to test the electrical connections on the motherboard, rather than waiting for the motherboard to indicate for itself whether it’s working or not. 

For instance, if the motherboard doesn’t power on, or doesn’t produce the beeping sound, spin the fan, and light up indicator lights, you may not be able to establish what is the problem if you are using the other methods. This makes the other testing methods limited and unreliable. 

The AstroAI Ohm Volt Amp Tester Multimeter eliminates this unreliability, allowing you to test and diagnose specific issues in the motherboard. Read more: How To Test A Motherboard With A Multimeter

The only downside of using a multimeter is the need to test many electrical connections, making it laborious. 

Also, it’s time-consuming, and you might spend more time testing the motherboard than the time you took to disassemble the PC.

For you to use the multimeter to test the motherboard, you will need to disassemble the PC and remove the motherboard from the casing. 

You can use the Kaisi Professional Precision Magnetic Screwdriver to disassemble the PC, and also to reassemble it after testing the motherboard.

Set the multimeter to around 200, which is the lowest Ohm setting. You can touch the probes together to ensure zero meter reading.

Then touch the bare metallic area of the computer chassis. 

The multimeter should retain zero reading. Check the PSU DC connector black wire pins and AC ground pin after removing the ATX connector.

These pins should have a zero reading also. While retaining the black probe on the computer chassis, use the red one to check colored wire pins values on the DC connector. 

These pins should have a 50 or above reading. Using the ATX 20-pin chart, check for the board connector’s pin numbers. Use the red probe to test the GND pins while maintaining the black probe on the chassis. The pins 17, 16, 15, 13, 7, 5, and 3 should have a zero reading. Any other multimeter reading is a sign of a faulty motherboard connector.

can testing mobo no cpu

Final Words About How To Test A Motherboard Without A CPU

The motherboard is the base of any computer system. Sometimes you may invest in a high-performance motherboard such as a gaming motherboard, only to fail to work as intended. If this happens, the first step should be to test it without a CPU. 

Using the Kaisi Professional Precision Magnetic Screwdriver, disassemble the PC for better access to the motherboard. Using the above methods, test to see whether the motherboard is working. If you want to diagnose a specific problem or the other methods fail, use the AstroAI Ohm Volt Amp Tester Multimeter to find out the issue.

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