Reset Tips

If your Apple computer is acting strangely, such as random restarts, muted audio, ports not reading/receiving information, etc., you can try to reset certain systems settings via a hardware-related reset.  Here is some general information on the whys, whens, and hows, of resetting your Apple computer.

***BEFORE YOU RESET NVRAM, PRAM, or SMC: Disconnect all drives, speakers, external displays and keyboards to make sure nothing interferes with the resetting process.***

What the SMC does

The SMC is responsible for these and other low-level functions on Intel-based Mac computers:

  • Responding to presses of the power button
  • Responding to the display lid opening and closing on Mac notebooks
  • Battery management
  • Thermal management
  • Sudden Motion Sensor (SMS)
  • Ambient light sensing
  • Keyboard backlighting
  • Status indicator light (SIL) management
  • Battery status indicator lights
  • Selecting an external (instead of internal) video source for some iMac displays

How to know if you need to reset the SMC

These symptoms might mean that an SMC reset is necessary:

  • Your computer's fans run at high speed, even though it isn't under heavy usage and is properly ventilated.
  • The keyboard backlight behaves incorrectly.
  • The status indicator light, if present, behaves incorrectly.
  • Battery indicator lights, if present, behave incorrectly on Mac notebooks with a non-removable battery.
  • The display backlight doesn't respond correctly to ambient light changes.
  • Your Mac doesn't respond when you press the power button.
  • Your Mac notebook doesn't respond properly when you close or open the lid.
  • Your Mac sleeps or shuts down unexpectedly and you can't turn it back on.
  • The battery doesn't charge properly.
  • Your MacBook or MacBook Pro doesn't charge through its built-in USB-C port.
  • Your MacBook or MacBook Pro doesn't recognize external devices that are connected to its built-in USB-C port.
  • The MagSafe power adapter LED, if present, doesn't indicate the correct charging activity.
  • Your Mac performs unusually slowly, even though its CPU isn't under an abnormally heavy load.
  • A Mac that supports target display mode doesn't switch into or out of target display mode as expected, or it switches into or out of target display mode at unexpected times.
  • The illumination around the I/O ports on a Mac Pro (Late 2013) doesn't turn on when you move the computer.

How to reset the System Management Controller (SMC) on your Mac

Before you reset the SMC

Try each of these steps in this order before you reset the SMC. Test the issue after each step to see if the issue still occurs.

  1. If your Mac isn't responding, press and hold the power button until it shuts down. You'll lose unsaved work in any open applications. Then press the power button again to turn on your Mac.
  2. Press Command-Option*-Escape to force quit any application that's not responding.
  3. Put your Mac to sleep by choosing Apple () menu >Sleep. Wake the computer after it's gone to sleep.
  4. Restart your Mac by choosing Apple menu >Restart.
  5. Shut down your Mac by choosing Apple menu > Shut Down, then press the power button again to turn on your Mac.

If you're using a Mac notebook that's having power or battery issues, follow these steps:

  1. Unplug the power adapter from your Mac and the electrical outlet for several seconds, then plug it back in.
  2. Choose Apple menu > Shut Down.
  3. After your Mac shuts down, remove and re-insert the battery if it's removable.
  4. Press the power button again to turn on your Mac.

If the issue still isn't resolved, you might need to reset the SMC using the steps below. 

* On some keyboards, the Option key is also labeled Alt.

How to reset the SMC on Mac notebooks

If you have a MacBook Pro (2018), skip ahead to the section that deals with your Mac.

To reset the SMC on a Mac notebook, first determine whether the battery is removable. Most older Mac notebooks have removable batteries. Mac notebooks that have nonremovable batteries include MacBook Pro (Early 2009 and later), all models of MacBook Air, MacBook (Late 2009), and MacBook (Retina, 12-inch, Early 2015 and later). Learn more about Mac notebook batteries.

If the battery is nonremovable:

  1. Choose Apple menu > Shut Down.
  2. After your Mac shuts down, press Shift-Control-Option on the left side of the built-in keyboard, then press the power button at the same time. Hold these keys and the power button for 10 seconds. If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.
  3. Release all keys.
  4. Press the power button again to turn on your Mac.
     

If the battery is removable:

  1. Shut down your Mac.
  2. Remove the battery. If you need help removing the battery, contact an Apple Authorized Service Provider or Apple Retail Store.
  3. Press and hold the power button for 5 seconds.
  4. Reinstall the battery.
  5. Press the power button again to turn on your Mac.

How to reset the SMC on Mac desktop computers

If you have an iMac Pro, skip ahead to the section that deals with your Mac.

Follow these steps for iMac, Mac mini, Mac Pro, and Xserve.

  1. Choose Apple menu > Shut Down.
  2. After your Mac shuts down, unplug the power cord.
  3. Wait 15 seconds.
  4. Plug the power cord back in.
  5. Wait 5 seconds, then press the power button again to turn on your Mac.

For Intel-based Xserve computers that aren't responding, you can shut down locally or by using remote commands. You can also press and hold the power button for 5 seconds.

How to reset the SMC on a Mac that has the Apple T2 Security Chip

Follow these instructions for Mac computers that have the Apple T2 Security Chip.

Mac desktop computers with the T2 chip

Try this first:

  1. Choose Apple menu > Shut Down.
  2. After your Mac shuts down, press and hold its power button for 10 seconds.
  3. Release the power button, then wait a few seconds.
  4. Press the power button again to turn on your Mac.

If that doesn't resolve the issue, follow these steps:

  1. Choose Apple menu > Shut Down.
  2. After your Mac shuts down, unplug the power cord.
  3. Wait 15 seconds.
  4. Plug the power cord back in.
  5. Wait 5 seconds, then press the power button again to turn on your Mac.
     

Mac notebook computers with the T2 chip

Try this first:

  1. Choose Apple menu > Shut Down.
  2. After your Mac shuts down, press and hold its power button for 10 seconds.
  3. Release the power button, then wait a few seconds.
  4. Press the power button again to turn on your Mac.

If that doesn't resolve the issue, follow these steps:

  1. Choose Apple menu > Shut Down.
  2. After your Mac shuts down, press and hold the right Shift key, the left Option key, and the left Control key for 7 seconds. Then keep holding those keys while you press and hold the power button for another 7 seconds.
  3. Release all three keys and the power button, then wait a few seconds.
  4. Press the power button again to turn on your Mac.
      

What the NVRAM/PRAM does

  • Status of Messages
  • Serial Port Configuration and Port definition
  • Alarm clock setting
  • Application font
  • Serial printer location
  • Autokey rate
  • Autokey delay
  • Speaker volume
  • Attention (beep) sound
  • Double-click time
  • Caret blink time (insertion point rate)
  • Mouse scaling (mouse speed)
  • Startup disk
  • Menu blink count
  • Monitor depth
  • 32-bit addressing
  • Virtual memory
  • RAM disk
  • Disk cache

Reset NVRAM or PRAM on your Mac

If your Mac has issues related to settings stored in NVRAM or PRAM, resetting it might help.

NVRAM (nonvolatile random-access memory) is a small amount of memory that your Mac uses to store certain settings and access them quickly. 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. The settings stored in NVRAM depend on your Mac and the devices that you're using with your Mac.

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

How to reset NVRAM

Option keyplusCommand keyplusP keyplusR key

Shut down your Mac, then turn it on and immediately press and hold these four keys together: Option, Command, P, and R. You can release the keys after about 20 seconds, during which your Mac might appear to restart.

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

If your Mac is using a firmware password, this key combination does nothing or causes your Mac to start up from macOS Recovery. To reset NVRAM, first turn off the firmware password.

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

    


Learn more

  • If you're using a desktop Mac instead of a notebook, and settings such as sound volume or time zone are reset every time you shut down and unplug your Mac, you might need to replace the battery inside your Mac. This small battery is on your computer's logic board, and it helps NVRAM retain settings when your Mac is unplugged. You can take your Mac to an Apple service provider to replace the battery.
  • If you experience issues with sleep, wake, power, charging your Mac notebook battery, or other power-related symptoms, you might need to reset the SMC (System Management Controller).
  • Resetting the SMC doesn't reset or otherwise change the contents of NVRAM or PRAM on Intel-based Mac models.