The Magic & Mystery Behind SMC and NVRAM / PRAM Resets

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Are you having problems with your MacBook, Mac mini or iMac? Have you tried SMC and PRAM resets?  If not, it’s worth trying. These magic resets can often fix simple software and hardware issues. They certainly can’t hurt and they just might help.

SMC reset? Sounds technical.

SMC, or System Management Controller, is a low-level function that does more or less what it says, it manages system controllers. Straight forward enough for you?

It regulates various hardware functions, mostly those related to power and power consumption.  Problems with a fan spinning too high, LED indicators not working, sleep/wake issues, sensors not reading and a whole host of other problems, can all be solved with an SMC reset. It handles a lot, but here’s a 99% complete list of problems you might run into that could be solved with an SMC reset:

  • MacBook does not respond to the opening and closing of the display.
  • MacBook does not respond to pressing the power button.
  • MacBook is not charging the battery properly.
  • MacBook is not regulating the temperature properly through use of the fans.
  • MacBook does not Sudden Motion Sensor (SMS)
  • MacBook does not adjust screen or keyboard brightness in response to ambient light.
  • Manually adjusting keyboard backlight brightness is non-functional.
  • MacBook’s white LED “status indicator light” does not behave properly.
  • MacBook’s battery status indicator lights are not responsive or otherwise do not behave properly.
  • Problems with an iMac using selecting an external display for video-out.

How does the SMC differ from NVRAM/PRAM?

About The Author

Brite Cheney

I am an English major at CSU, Chico with a lifelong interest in computers and technology, and joy for writing about all things tech.

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Hi man, good article. I ve been experiencing problems with keyboard and mouse. Suddenly the left button on mouse start behavig like right button. And command and option buttons start misbehaving too. I ve been experiencing this since the upgrade from yosemite to sierra. I thought this was going to stop when I upgraded from sierra to high sierra, but no. The recovery partition is gone, just for the récord. I read on internet that other users had experienced this same error (recovery partition gone) when they upgraded to high sierra. I have been trying to do the pram reset… Read more »


Hii, I also have the problem. When I power on my Mac book air the login screen shows name and password,then I hit keys it shows some crazy symbol’s and can’t login . I tried cmd+optn+P+R. My left option key isn’t working, then I checked in key board preferences I found that the option key is pressed. Then I restart my Mac I also had the same problem. Please help?