macOS: How to Reset Mac SMC and NVRAM, and Why You Would Need To

3 minute read
| How-To

The System Management Controller, controls many low-level functions on your Intle-based Mac. But there are certain times where you may need to reset it. Here is how to reset Mac SMC, and the warning signs to look out for to find out if you need to.

What the SMC Does

  • Responding to power button presses
  • Responding to the display lid opening and closing on MacBooks
  • Battery management
  • Thermal management
  • Sudden Motion Sensor (SMS)
  • Ambient light sensing
  • Keyboard backlighting
  • Status indicator light (SIL) management
  • Battery status indicator lights
  • Choosing an external video source for some iMac displays
Image of a motherboard. Reset Mac SMC by following these steps.

Photo by Alexandre Debiève on Unsplash

SMC Warning Signs

If you run into any of these issues, that may be a sign that your SMC needs to be reset:

  • The keyboard backlight doesn’t work right, or at all
  • The battery or status lights aren’t working right
  • Your Mac doesn’t turn on when you open the lid
  • The power adapter light doesn’t work right, or doesn’t reflect what it’s doing (green for charged, orange for charging)
  • The fan runs at high speed, even if you aren’t doing CPU-intensive stuff
  • The trackpad doesn’t work
  • Your Mac won’t connect to Wi-Fi
  • Your Mac runs slowly, even if you aren’t doing CPU-intensive stuff
  • Your Mac shuts down slowly

Page 2: Resetting the SMC

4 Comments Add a comment

  1. furbies

    Why does it take 3 pages for such a short and simple article ?

    Is TMO taking to this style of publishing simply so it can show 3 sets of adverts ?

    • Andrew Orr

      Not at all. We want to keep our mobile readers in mind, and in my experience it’s kind of a pain to scroll through one, long article on my iPhone.

    • mbmoore@mbmoore.com

      Would you rather pay for the article yourself? MacObserver has to make money to stay in business just like everybody else.

  2. neohavix

    I did this a couple of days ago for my 2010 15″ MBP. It was working properly until I updated to High Sierra. When it went through the process, it failed. So, I asked @applesupport for assistance. To make a long story short, I did the SMC first. It did not work. Then I did NVRAM. Somewhat worked. I had to do a First Aid on my MBP per @applesupport. It turned out that my disk is shot.

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