How to Reset PRAM, SMC, and NVRAM on Your Mac (and Why)

PRAM (Parameter RAM) is a type of RAM that is used by your Mac to store certain settings and access them quickly.

Why reset PRAM?

You should reset your PRAM if you're experiencing problems related to any of the following:

• 32-bit addressing
• Alarm clock setting
• Application font
• Attention (beep) sound
• Autokey delay
• Autokey rate
• Caret blink time (insertion point rate)
• Disk cache
• Double-click time
• Menu blink count
• Monitor depth
• Mouse scaling (mouse speed)
• RAM disk
• Serial Port Configuration and Port definition
• Serial printer location
• Speaker volume
• Startup disk
• Status of Messages
• Virtual memory
• Wireless networks randomly won't appear
• Other miscellaneous issues

Generally, I always reset the PRAM as the first troubleshooting step.

How to reset PRAM

To reset your Mac's PRAM, do the following:

1. Shut down your Mac.
2. Turn it back on by pressing and releasing the power button.
3. Immediately press and hold the following four keys together: [⌥Option], [⌘Command], [P], [R]
4. If your Mac plays a startup sound, release the keys after the startup sound chimes a second time. Otherwise, release the keys after the Apple logo appears and disappears a second time.

Learn more about PRAM from Apple support.

The System Management Controller (SMC) is related more closely to power management and hardware issues, especially on MacBooks.

Why reset SMC?

If you're experiencing issues related to any of the following, it's time to reset your SMC:

• Battery and charging
• Behavior when opening and closing the lid of a notebook computer
• Computer or screen won't wake
• Fans and other thermal-management features
• Indicators or sensors such as status indicator lights (sleep status, battery charging status, and others), the sudden motion sensor, the ambient light sensor, and keyboard backlighting
• Power, including the power button and power to the USB ports

How to reset SMC

There are a few methods for resetting SMC. Choose the one for your Mac model:

All MacBook Air models, as well as MacBook and MacBook Pro models mid-2009 or later (excluding the mid-2009 13" MacBook)

1. Shut down your Mac.
2. Press and hold the following three keys at the same time: [⇧Shift], [⌃Control], [⌥Option].
3. While still holding the three keys, hold the power button as well.
4. Hold these four keys for 10 seconds and then release them.
5. Wait a few seconds before pressing the power button.

Notebook computers with the T2 chip, including many newer MacBooks

1. Shut down your Mac.
2. Press and hold the following three keys at the same time: [⌃Control] and [⌥Option] on the left side of your keyboard, and [⇧Shift] on the right side of your keyboard. Your Mac may or may not turn on.
3. Hold these three keys for 7 seconds.
4. While still holding the three keys, hold the power button as well.
5. Hold these four keys for 7 seconds and then release them.
6. Wait a few seconds before pressing the power button.

All desktop computers (Mac Pro, etc.)

1. Shut down your Mac and unplug the power cord.
2. Wait 15 seconds and plug the power cord back in.
3. Wait 5 more seconds and then press the power button.

Learn more about SMC from Apple support, as well as how to reset SMC on early- and pre-2009 Mac computers.

The NVRAM (nonvolatile random-access memory) stores similar information to PRAM.

Why reset NVRAM?

Reset your NVRAM if you experience problems related to any of the following:

• Display resolution
• Recent kernel panic information
• Sound volume
• Startup-disk selection
• Time zone
• You see a question mark briefly before your Mac starts up
• Your Mac boots into the wrong startup disk

How to reset NVRAM

The NVRAM reset process is the same as the PRAM process:

1. Shut down your Mac
2. Turn it back on by pressing and releasing the power button.
3. Immediately press and hold the following four keys together: [⌥Option], [⌘Command], [P], [R]
4. If your Mac plays a startup sound, release the keys after the startup sound chimes a second time. Otherwise, release the keys after the Apple logo appears and disappears a second time.

Learn more about NVRAM from Apple support. Be sure to check out our Apple interest page for more troubleshooting and maintenance guides.