Mac: Signs of a Bad Logic Board

The logic board on a Mac is another term for the motherboard, which contains the circuitry and components that allow your computer to function. Whether you have a Mac laptop or desktop, common logic board failure signs include problems with the computer's power, graphics, ports, fans, Bluetooth and unusual behaviors. Issues can be as minor as a single USB port not working to as bad as the computer not coming on at all. While these common Mac logic board failure signs also overlap with smaller hardware and software issues, understanding the signs of a bad logic board can help you determine if it's time to get your Mac checked out at an Apple Store or other authorized Mac repair center.

Since the logic board controls the computer's components, one sign of a Mac logic board failure is the computer not turning on at all when you press the power button. While a dead battery could also be the culprit for a MacBook with this issue, failure to boot even with the power cord plugged in signals possible logic board problems. In some other cases, your computer may power on but shut down before booting is complete, or it may boot normally but shut down without warning at random times when you're using it. Another issue you might see is your computer completely freezing to the point where you have to hold down the power button to force it off and restart. While this problem could be as simple as bad memory modules, it could also mean your logic board is failing.

Another sign of a Mac logic board failure involves your computer's display not coming on or behaving erratically. You might hear your computer boot up and the fan come on, but the backlight never comes on, so you see nothing on the display or see only a faint image. This issue may even persist when you try to connect an external monitor to your Mac, which indicates a graphics issue on the logic board rather than just a faulty or worn display. If the screen does come on, you may experience other issues like corrupted graphics where the image on the screen is scrambled or has lines of random colors going through it.

Because the logic board contains your ports and is where other computer components connect, you can experience a range of issues with port, audio and other component failures. When a port on the logic board is failing, you may notice your computer no longer recognizes devices plugged into the port or does not provide enough power to them. If the issue lies with the logic board's audio component, you may hear no sound or have issues getting external speakers or headphones working when you plug them into your computer's audio jack. You may also have problems with your Mac's integrated webcam, Bluetooth peripherals or Wi-Fi not working correctly.

Other common logic board failure signs can include your battery not charging when you have the power adapter connected and your computer's fan never coming on or running constantly regardless of how demanding your work is. You might also hear strange clicking or grinding sounds coming from the computer's logic board, or you might encounter frequent error messages on the screen that refer to the computer having to unexpectedly reboot due to some system issue or a kernel panic. While strange noises or error messages alone don't guarantee your logic board is bad, they can signal it's time to back up your data and prepare to take your computer in for a checkup.

Your Mac's logic board may fail due to a factory defect or extensive use, but accidents like falls and spills also cause damage. In addition, computer use resulting in overheating and lack of airflow can harm the logic board and cause premature failure. If your logic board fails due to a factory defect or regular use, you can take advantage of your Apple warranty for repair or replacement.

If the machine is out of warranty or the problem is from misuse, you'll have to pay to exercise available repair options. When your Mac is very old or multiple repairs are needed, it may be more cost-effective to get a new computer than to spend hundreds fixing the logic board. For example, Forbes warns that repairing newer Apple MacBook Pro logic board problems also requires replacing the laptop's solid-state drive, which can add to the cost significantly if there's no warranty.