How to reset the NVRAM/PRAM and SMC on your Mac

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If your Mac’s acting a little oddly, you’ll probably go through a familiar routine to try and solve the problem. Reboot the Mac, then boot it in safe mode, and if that doesn't sort it out it's usually a visit to fix permissions in Disk Utility. But what else can you do?

If the usual quick fixes don't work, you might need to reset your Mac’s NVRAM (non-volatile random access memory) or SMC (System Management Controller) to fix the problem. Resetting them can get rid of all kinds of odd quirks, like the Mac forgetting which Startup disk to use or mouse settings changing themselves.

 

What is NVRAM?

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NVRAM is used to store some system settings on a Mac, and access them quickly. These can include things like the screen resolution, sound volume, and time & date settings.

Non-volatile means it doesn’t lose its data when there’s no power, just like flash memory in a USB drive. It does the same job for modern Intel-based Macs that PRAM (Parameter RAM) used to do in older PowerPC-based Macs.

 

Resetting the NVRAM or PRAM

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To reset the NVRAM or PRAM:

 

1.

Shut down your Mac.

2.

Press the power button, then immediately press and hold the following keys: Cmd () + Opt () + P + R.

3.

If your Mac plays a startup sound (which is most pre-2017 models), keep the buttons pressed until your hear the second chime.

4.

If you have an iMac Pro, let go of the keys after you see the Apple logo appear and disappear twice.

Resetting the NVRAM fixes lots of issues, but it also resets many settings to their defaults. When the Mac restarts, you'll need to visit System Preferences to adjust any settings that have been reset. These can include things like display, volume, keyboard and mouse settings.

 
 
 
 
reset nvram and pram on a mac

What is the SMC?

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If your issue is power-related, you might fix it by resetting the SMC. It controls things like indicator and keyboard lighting, battery and thermal management, and even what happens when the notebook lid is opened or closed.

Maybe the MacBook's battery isn't charging like it should, or the MagSafe connector light doesn't work as it should. Perhaps your computer's fan is running at full speed, even if it isn't working very hard. Whatever the issue, if it's in some way power-related, resetting the SMC might just solve the problem.

 

Resetting the SMC

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Check which method to use based on your Mac's model and age.

Mac notebooks

Up to 2009, most MacBooks had removable batteries, and most models built since then have built-in ones.

 

MacBook models with fixed batteries

 

1.

Go to Apple () > Shut Down.

2.

When the Mac's turned off, press and hold the Shift + Control + Option keys on the left of the keyboard. While you're holding those down, press and hold the Power button for 10 seconds.

3.

Let go of all the keys.

4.

Press Power to start your Mac.

MacBooks with a removable battery

 

1.

Go to Apple () > Shut Down.

2.

Remove the battery. If you're not sure how to do that, check with an Apple Authorised Service Provider

3.

Press and hold the Power button for 5 seconds.

Replace the battery, the press the Power button to restart your Mac.

Mac desktop computers

The SMC is reset in the same way on all Apple desktop computers with the exception of the iMac Pro (2017 onwards).

 

If you have an iMac Pro

 

1.

Go to Apple () > Shut Down

2.

Press and hold the Power button for 8 seconds, then release it.

3.

Wait another 5 seconds, then turn the Mac back on.

For all other desktop Macs

 

1.

Go to Apple () > Shut Down.

2.

Unplug the power cable and wait for 15 seconds

3.

Reconnect the mains cable, then wait for another 5 seconds.

4.

Press the Power button to restart your Mac.

Hopefully your Mac should now be quirk-free and running smoothly, but you can contact an expert from Team Knowhow for more help if you need to.

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