Resetting the SMC (System Management Controller) on Your Mac

When your Mac misbehaves, reset the SMC

MacBook Air at Apple Store
There are a few different methods to reset the SMC. Spencer Platt/Getty Images News

The System Management Controller (SMC) controls a number of Mac core functions. The SMC is hardware incorporated into the Mac's motherboard. Its purpose is to free the Mac's processor from having to take care of rudimentary hardware functions. With many core tasks performed by the SMC, it is no wonder that resetting the SMC to its default state can fix problems.

What the SMC Controls

The SMC performs the following functions, which vary by Mac model:

  • Responds to the press of the power button, including deciding whether the press is for a power off, sleep, or an accidental misstep by your cat
  • Detects and responds to the opening or closing of the lid of a portable Mac
  • Manages a portable's battery performance, including charging, calibration, and displaying remaining battery time
  • Handles the thermal management of the Mac's interior by sensing the temperature at various places inside the Mac and then adjusting fan speed to create or reduce airflow
  • Uses the sudden motion sensor to respond to the sudden motion of a Mac laptop and acts to prevent damage
  • Detects ambient lighting conditions and sets appropriate lighting levels for devices
  • Controls keyboard backlighting
  • Controls built-in display backlighting
  • Controls the status indicator lights that are present on or in the Mac
  • Selects external or internal video sources on iMacs with video input capabilities
  • Starts hard drive spin downs and power-up sequences
  • Controls sleep mode functions
  • Controls trackpad functions for Mac models with trackpads

    Signs You Need to Reset the SMC

    Resetting the SMC is not a cure-all, but it fixes many symptoms a Mac may suffer from, including:

    • Erratic sleep mode performance, including not waking from or not entering sleep
    • Entering sleep unexpectedly, even while you are actively working on it
    • Mac laptops not responding to lid opening or closing
    • Failure to respond to the power button being pressed
    • Power indicator not displaying or displaying incorrectly
    • Sluggish performance, even when Activity Monitor shows little CPU usage
    • Target Display Mode not working correctly
    • Battery not charging or taking excessive time to charge
    • USB ports not working
    • Wi-Fi hardware reported as missing or not working
    • Bluetooth not working
    • Fans running too rapidly
    • Display backlight not responding to ambient light-level changes
    • Status indicator lights not working correctly or stuck in a static state
    • Bouncing Dock icons that keep bouncing without the associated app launching
    • Mac Pro (2013) port illumination fails to turn on or off

    How to Reset Your Mac's SMC

    The method for resetting your Mac's SMC depends on the type of Mac you have. All SMC reset instructions require shutting down your Mac first. If your Mac fails to shut down, try pressing and holding the power button until the Mac shuts down, which usually takes 10 seconds or so.

    Reset Mac Notebooks With User-Removable Batteries

    1. Shut down the Mac.
    2. Remove the battery.
    3. Press and hold the power button for at least five seconds.
    4. Release the power button.
    5. Reinstall the battery.
    6. Turn on the Mac.

    Reset Mac Notebooks Without User-Removable Batteries

    1. Shut down the Mac.
    2. On the built-in keyboard (this does not work from an external keyboard), simultaneously press and hold the left Shift, Control, and Option keys while you press the power button for at least 10 seconds. (If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.) Release all keys at the same time.
    3. Press the power button to start the Mac.

    Reset Mac Desktops and Notebooks With the Apple T2 Chip

    If you have an iMac Pro or MacBook Pro model from 2018 with the Apple T2 chip:

    1. Shut down the Mac.
    2. Press and hold the power button for 10 seconds.
    3. Release the power button and wait a few seconds.
    4. Press the power button again to turn on the Mac.

    As an alternative for the iMac Pro with T2 chip, you can:

    1. Shut down the Mac.
    2. Unplug the power cord.
    3. Wait 15 seconds.
    4. Plug in the power cord.
    5. Wait five seconds.
    6. Press the power button to turn on the Mac.

    As an alternative for the MacBook Pro with T2 chip:

    1. Shut down the Mac.
    2. Press and hold the right Shift key, the left Option key, and the left Control key for seven seconds. Continue to hold them down while you press the power button for another seven seconds.
    3. Release all the keys at the same time.
    4. Press the power button to turn on the Mac.

    Mac Desktops (Mac Pro, iMac, Mac mini)

    1. Shut down the Mac.
    2. Unplug the Mac's power cord.
    3. Wait 15 seconds.
    4. Reconnect the Mac's power cord.
    5. Wait five seconds.
    6. Start your Mac by pressing the power button.

    Alternative SMC Reset for Mac Pro (2012 and Earlier)

    If you have a 2012 or earlier Mac Pro that isn't responding to the normal SMC reset, you can force a manual SMC reset by using the SMC reset button located on the Mac Pro's motherboard.

    1. Shut down the Mac.
    2. Unplug the Mac's power cord.
    3. Open the Mac Pro's side access panel.
    4. Just below the Drive 4 sled and adjacent to the top PCI-e slot is a small button labeled SMC. Press and hold this button for 10 seconds.
    5. Close the Mac Pro's side door.
    6. Reconnect the Mac's power cord.
    7. Wait five seconds.
    8. Start the Mac by pressing the power button.

    Now that you have reset the SMC on your Mac, it should be back to operating as you expect. If the SMC reset didn't fix your problems, you can combine it with a PRAM reset. Although the PRAM works differently than the SMC, it can store a few bits of information that the SMC uses.

    If you're still having problems, you may want to run the Apple Hardware Test to rule out a defective component on your Mac.