Reset power management and NVRAM

If your Mac has issues which aren't exactly either software or hardware related, such as:

  • misbehaving USB ports,
  • problems with Wi-Fi,
  • issues with sound or display brightness,
  • insufficient battery charging,
  • random sleeps or wake-ups,

you could try these two quick fixes - resetting power management controller, followed by erasing parametric memory. The first one controls distribution of power to different parts of your Mac, and the second holds certain setting.

You won't lose any data, only some little details such as speaker volume or display brightness. But it might bring a seemingly malfunctioning USB port back to life.

A reason why the power management controller became confused in the first place could be diverse, such as using a weaker or third-party adapter, or spikes in power supply. Always use the charger with proper wattage and also consider investing to a power surge protector.

Power management reset

  • Shut down your Mac first. Then:


  • Using the built-in keyboard, press Shift, Control and Option on the left side of the keyboard, then press the power button at the same time. Hold these keys and the power button for 10 seconds.
  • Release all keys. Wait 5 seconds and start your notebook normally.

Notebooks (with removable battery)

  • Remove the battery.
  • Press and hold the power button for five seconds.


  • Unplug the power cord.
  • Wait 15 seconds.
  • Plug the power cord back in.
  • Wait five seconds.

NVRAM reset

  • Then turn it on and immediately hold down these four keys together: Option, Command, P, and R.
  • Keep holding the keys for about 20 seconds, during which your Mac might appear to restart.
  • You can release the keys after the second startup sound.

If it won't help, please bring it at your nearest convenience - we will test it with Apple Diagnostic Tools.

More info at Apple Support:


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