How to reset NVRAM, PRAM, and SMC on a Mac

If you’ve ever had a problem with your Mac being unable to start up regularly or with some services not working, you had to restart it, run Disk Utility, or try macOS Safe Boot Mode.

We have an article in which we explain what can you do if your Mac won’t turn on. However, we want to walk you through the simple procedures you can do to try and fix it before you need to take the equipment to Apple’s official technical service.

In the repairs directory that you can try, there are a few optimization processes that sometimes tend to work, such as removing NVRAM, restarting PRAM, or resetting the system we know as SMC.

How to remove NVRAM or PRAM

It is one of the quick fixes considered among Mac users that allows you to delete what is stored in the random access memory of PRAM, a small part of the memory saved by the battery of every Mac that stores data. information about the computer before loading the operating system. .

If it turns out that these memory settings have been changed or lost, your Mac may not start correctly or display strange behavior during system startup.

Most modern Macs no longer use PRAM; instead, they use something called NVRAM (NV for non-volatile), although for the same purpose of storing information about boot disk, speaker volume, screen resolution, time zone and other data of interest.

NVRAM corruption is quite common, but if your Mac seems to take forever to boot, doesn’t know which drive to boot, or boots with the wrong screen resolution, resetting NVRAM doesn’t hurt. It’s fast and secure.

  1. Shut down your Mac computer.
  2. Turn it on again and as soon as it is activated, press and hold the keys: ‘Command-Option-P + R’.
  3. Hold down the buttons for at least 20 seconds. Then release them and let your Mac continue to start normally. If you have an older Mac that rings at startup, press and hold the keys until you hear a second beep.
  4. Next, check the ‘Startup Disk, Display, and Date & Time’ panels in System Preferences to make sure they are set correctly.

Si mantienes presionada la tecla ‘Comando-Opción-P + R’ al inicio y no ves nada más que una pantalla gris que no cambia durante varios minutos, sin el logotipo de Apple, sin barra de progreso, sin un segundo timbre de inicio, do not panic.

Your Mac may not be logging your keystrokes due to issues with a USB device. Disconnect all USB devices connected to your computer (except your keyboard, if it’s a wired keyboard), and hold down the power button until the Mac turns off completely .

MacOS recovery dome

Press again to turn on the Mac and again hold the “Command-Option-P + R” keys. If that doesn’t work and you’re using an external Bluetooth keyboard, try connecting a USB keyboard instead.

Once you can reset NVRAM as we explained in the previous steps, you can disconnect it and go back to using your bluetooth keyboard that you use regularly, if that’s what you want.

Reset SMC System

Another component of Equipment On your Mac that stores key aspects of your configuration is the System Management Controller (SMC).

This circuit is responsible for power management, temperature monitoring and fan control, status lights, keypad backlighting, and some other components.

If your SMC is corrupted, you might experience issues like excessive fan noise, slow performance despite the activity monitor not showing the processor is overloaded, applications that take forever to start, batteries not draining. not charging correctly, problems coming out of hibernation, etc. .

(You can see a full list in the Apple support page). As with NVRAM, resetting the SMC to factory default settings can resolve a whole list of issues.

Apple says you shouldn’t reset SMC without first trying other solutions like forcing problematic apps to quit and restarting your Mac. However, Apple does not mention any negative consequences of resetting the SMC.


I have restarted the SMCs of my Macs over the years on several occasions without any apparent ill effect on the system, and sometimes this has proven to be the solution to a specific problem. Before resetting your SMC, you must shut down your Mac.

After that, the procedure will vary depending on the type of Mac you have.

  • Mac or iMac for dessert: Unplug the power cord (from the Mac or the electrical outlet). Wait 15 seconds and reconnect it. Then wait another 5 seconds and turn the Mac back on.
  • Laptops with T2 chip: Off. Press and hold the power button for 10 seconds, then release it. After a few seconds, press the power button to turn on your Mac. If this does not reset the SMC, turn it off. On the laptop keyboard, hold down the “ Control-Option-Shift ” key (your Mac may turn on). Press and hold these keys for 7 seconds, then press and hold the power button. If your Mac is on, it will turn off while you hold down the keys for an additional 7 seconds. Then release the keys, wait a few seconds and turn the laptop back on.
  • Laptops (without T2 chip) with non-removable batteries– Shut down and unplug your Mac. On the built-in keyboard, hold down the “Shift, Option, and Control” keys on the left side and press and hold the power button for 10 seconds. Plug in the AC adapter, then turn on your Mac.
  • Laptops (without T2 chip) with removable batteries: Shut down your Mac, unplug the power cord, and remove the battery. Press and hold the power button for 5 seconds, then release it. Replace the battery, plug in the power cord, and turn on your Mac as usual.

While neither of these procedures is guaranteed to fix the problem, both can resolve a range of issues related to starting up and keeping your Mac running smoothly. You don’t lose anything and you can save money before you take it to an official technical service. .

Our article on how to reinstall macOS if system recovery does not work.

This information was published by Joe Kissell in MacWorld United States.

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