Secret Apple Mac startup options to fix problems that won't go away

Hold down these keys when the Mac starts up to fix a variety of strange problems with Apple iMacs and MacBooks. If you have tried everything else and problems persist, try these tricks.

What is NVRAM and PRAM on the Mac?

The Apple Mac has a small amount of special memory that it uses to store a variety of important system settings. On old Macs it is called PRAM, which stands for Parameter RAM, but on recent Macs it is called NVRAM (Non-Volatile RAM). Basically, it is memory that retains its contents even when the power is switched off.

MacBooks have a big battery of course, but desktop iMacs have little one too, so they can maintain the NVRAM contents. If an iMac keeps forgetting things like the sound volume or time zone, it may be becuse the battery is dead. A new one is required - get expert help because it is on the motherboard.

Even if the battery is OK, for some unknown reason the contents of this memory can become corrupted or it might contain wrong settings and this can affect the running of the computer.

NVRAM or PRAM is used to store information like the speaker volume so that it is set at the same level next time you power on. It stores the name/location of the startup disk in case you have two or more drives, or partitions with Bootcamp and so on. It remembers the screen resolution so it can restart with the same settings, and more.

Any problems you are having with these components, and a few more, could be caused by corrupt NVRAM or PRAM and may be fixed by clearing it and started with a clean slate.

Reset the NVRAM or PRAM on the Mac

To do this, turn up the volume to the maximum, then power off your Mac. Press the power button and straight away press and hold down the Command+Option+P+R keys. Relase the keys after the second startup sound (old Macs) or after the second Apple logo appears (new Macs). Let go of those keys and the Mac will then boot up as it normally does, but with default NVRAM/PRAM settings.

After resetting the NVRAM/PRAM, you might need to open System Settings and select the startup disk, screen resolution, time, and sound if the defaults are not to your liking.

Reset the SMC on the Mac

The NVRAM/PRAM is not the only component that stores system settings and there is another called the SMC, short for System Management Controller. This performs a lot of functions and among them is the system fan, if your Mac has one. If the fan is blowing all the time then resetting the SMC can help.

The SMC controls all the lights, like the keyboard backlight, the status indicator, battery indicator, and display backlight. It controls the power, including the power button, battery charging, sleep mode, opening and closing the lid. It controls the CPU, which affects the system performance, the bounce of Dock icons, video mode switching and more.

Resetting the SMC should be done as a last resort when you have tried everything else and have failed to solve the problem you are having. It is not the first thing to try because it has such wide-ranging effects on the system. You just might need to configure a lot of settings afterwards.

On a MacBook with a T2 security chip, which was introduced in 2018, shut down the MacBook and then press and hold the power button for 10 seconds. Let go, then press the power button to start the MacBook as normal.

It does not reset it, but this procedure can fix some problems. If it does not, shut down the Macbook. On the left side of the keyboard, press Ctrl+Option+Shift for 7 seconds, the Mac might turn on. Then press the power button, if your Mac is on, it will turn off. Keep holding the keys down for another 7 seconds. Release them all and tap the power button to turn on the Mac.

On older MacBooks with no T2 chip made before 2018, shut down the computer. Press the Shift+Ctrl+Option buttons on the left side of the keyboard and the power button all at the same time. Hold them for 10 seconds, then release all of the buttons. Switch on with the power button in the usual way.

Not sure if your MacBook has a T2 chip? Click the Apple menu, hold down Option and click System Information. Select Controller in the Hardware section and you will see, or not see, the T2 chip.

The iMac and Mac mini are different again. Shut down the Mac and unplug the power cable. Wait 15 seconds and plug the power cable back in. Five seconds later, press the power button to turn on the Mac. The timing is probably important, so have your watch, an Apple Watch of course, next to you when you do this.

Start the Mac in safe mode

Start the Mac in safe mode by tapping the power key to turn it on and then hold down Shift. It is a minimal startup and extensions, non-standard fonts and other things are not loaded. Caches are cleared and the disk is checked. You don't have to do anything in safe mode. Just wait a couple of minutes and restart as normal.

Use the Diagnostics Utility

Hold down D while starting the Mac to start the Apple Diagnostics utility - let go when you see a screen asking for your language. It spends a few minutes checking the Mac and repairing things if necessary and it can fix certain problems. Shut down or restart when it has finished.

Start in verbose mode

When the Mac starts up, all you see is a progress indicator slowly working its way across the screen. However, unseen in the background, the macOS is working furiously performing all sorts of actions, loading things and getting them ready for use. If you want to see what is going on when the Mac starts up, hold down Command+V for verbose mode. It lists on the screen everything it does. Most of it will not make sense, but you may get lucky and see an error message or see the point at which it is getting stuck starting up.

Choose a startup disk

Hold down the Option key when starting and a list of startup disks is displayed. This is useful if you have Windows in Boot Camp or macOS installed on an external drive. Use the arrow keys to select a drive and press Enter to start from it.

Do you use a firmware password on your Mac?

Important! If you use a firmware password on your Mac for extra security, several of the keyboard startup options are disabled. They won't work! Disable this feature if you want to use any of the startup items listed above.

Use the Command+R key combo when starting a Mac to go to the macOS Recovery screen. Go to the Utilities menu and select either Startup Security Utility or Firmware Password Utility. Click Turn Off and enter the password. You do know the firmware password, right? If you don't, you need to take your Mac to an Apple Store with proof of purchase to get it reset.

After using the startup keyboard options, you can turn on the firmware password again if you need it.