How to reset your MacBook SMC & NVRAM / PRAM

by Azrul Abas on February 12, 2022

Man working on his MacBook

SMC

The System Management Controller (SMC) is responsible for managing behaviors related to power - which include the power button and power to USB ports - as well as battery and charging. By resetting the SMC, it will not affect the contents of NVRAM or PRAM.

It is common to reset the SMC after doing a MacBook Pro battery replacement in Singapore whenever there seems to be an issue with sleep, wake, power, battery or charging of your MacBook. 

How to do an SMC reset on computers that have the T2 chip*:

 

  • Mac Pro (2019)
  • MacBook Air (Retina, 13-inch, 2020)
  • MacBook Air (Retina, 13-inch, 2019)
  • MacBook Air (Retina, 13-inch, 2018)
  • MacBook Pro (13-inch, 2020, Two Thunderbolt 3 ports)
  • MacBook Pro (13-inch, 2020, Four Thunderbolt 3 ports)
  • MacBook Pro (16-inch, 2019)
  • MacBook Pro (13-inch, 2019, Two Thunderbolt 3 ports)
  • MacBook Pro (15-inch, 2019)
  • MacBook Pro (13-inch, 2019, Four Thunderbolt 3 ports)
  • MacBook Pro (15-inch, 2018)
  • MacBook Pro (13-inch, 2018, Four Thunderbolt 3 ports)

  •  

    1. Shut down your Mac.

    2. On your built-in keyboard, press and hold all of the following keys. Your Mac might turn on.
    - Control button on the left side of your keyboard

    - Option (Alt) button on the left side of your keyboard

    - Shift on the right side of your keyboard 

    3. Keep holding all three keys for 7 seconds, then press and hold the power button as well. If your Mac is on, it will turn off as you hold the keys.

    4. Keep holding all four keys for another 7 seconds, then release them.

    5. Wait for a few seconds, then press the power button to turn on your Mac.

     

    How to do an SMC reset on computers without the T2 chip*:

    Notebook computers with a non-removable battery:

  • MacBook Pro, mid-2009 to 2017
  • MacBook Air , 2017 or earlier
  • All MacBook models, except MacBook (13-inch, Mid 2009). 
  •  

    1. Shut down your Mac.

    2. On your built-in keyboard, press and hold all of these keys:

    3. Shift on the left side of your keyboard

    4. Control on the left side of your keyboard

    5. Option (Alt) on the left side of your keyboard

    6. While holding all three keys, press and hold the power button as well

    7. Keep holding all four keys for 10 seconds.

    8. Release all keys, then press the power button to turn on your Mac

     

    Notebook computers with a battery that can be removed:

  • MacBook Pro & MacBook, early 2009 or earlier
  • MacBook (13-inch, Mid 2009). 

  • 1. Shut down your Mac.

    2. Remove the battery.

    3. Press and hold the power button for 5 seconds.

    4. Reinstall the battery.

    5. Press the power button to turn on your Mac.

     

    NVRAM / PRAM

    NVRAM (nonvolatile random-access memory) on the other hand is a small amount of memory that your Mac uses to store certain settings and access them quickly. The PRAM (Parameter RAM) stores similar information, and the steps for resetting NVRAM and PRAM are the same.

    Settings that can be stored in NVRAM include sound volume, display resolution, startup disk selection, time zone and recent kernel panic information. This can also happen after a MacBook Air or Pro battery replacement service.

    If you're experiencing issues related to these settings or others, resetting NVRAM may help. For example, if your MacBook Pro starts up from a disk other than the one selected in Startup Disk preferences or a question mark icon briefly appears before start up, you may need to reset NVRAM.

    How to reset NVRAM

    1. Shut down your Mac

    2. Then turn it on and immediately press and hold these four keys together: Option, Command, P and R.

    3. You can release the keys after about 20 seconds, during which time your Mac may appear to restart.

    4. On Mac computers that play a startup sound, you can release the keys after the second startup sound.

    5. On Mac computers that have the Apple T2 Security Chip*, you can release the keys after the Apple logo appears and disappears for the second time. 

    When your Mac finishes starting up, you may want to open System Preferences and adjust any settings that have been reset, such as sound volume, display resolution, startup disk selection or time zone.

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