After resetting NVRAM, you may need to reconfigure settings for speaker volume, screen resolution, startup disk selection, and time zone information.Power related settings can be controlled by the System Management Controller (SMC) on your Mac. If you are experiencing issues with powering on your computer, sleep, wake, charging your Mac notebook battery, or other power-related symptoms, you might need to reset the SMC instead.
Resetting the System Management Controller (SMC)
In some situations you might need to reset your computer's System Management Controller (SMC).
Before resetting the SMC:
You should only do an SMC reset after you've tried all other standard troubleshooting. Try each of the following steps in this order before
you reset the SMC. Test the issue after completing each troubleshooting step to see if the issue still occurs.
If you're using a Mac notebook and it's having issues related to power or the battery:
If the issue still isn't resolved after following these steps, you might need to reset the SMC.
On Mac notebooks with non-removable battery
Mac notebook computers that have a battery you should not remove include: MacBook Pro (Early 2009) and later, all models of MacBook Air, MacBook (Late 2009), and MacBook (Retina, 12-inch, Early 2015).
To reset the SMC:
On MagSafe power adapters, the LED might change states or temporarily turn off when you reset the SMC.
On Mac notebooks with removable battery
Older MacBook and MacBook Pro computers have removable batteries. Learn about removing the battery on MacBook and MacBook Pro.
To reset the SMC:
On Mac Pro, iMac, Mac mini, and Xserve
To reset the SMC on Intel-based Mac Pro, iMac, and Mac mini computers, as well as Xserve:
For Intel-based Xserve computers that are not responding, you can shut down locally or by using remote commands. You can also shut down by pressing and holding the power button for five seconds.