MB-Air

The System Management Controller or SMC is responsible for many low-level functions on Intel-based Macs. Wondering whether you have an Intel-based Mac? If your machine was purchased later than 2006, chances are you do. Intel-based Macs, as you may have guessed by now, use Intel processors. Earlier Macs used a processor built by IBM, Motorola, and Apple, and are called PowerPCs. The SMC equivalent in PowerPCs is called Power Management Unit or PMU.

What is the Systems Management Controller? 

The SMC is what makes the computer respond to presses of the Power button, for example, and is responsible for battery management, thermal management, the sudden motion sensor or SMS, ambient light sensing, and keyboard backlighting. The SMC also controls how the computer responds when users open or close their display lids.

Here are ten scenarios where you may need a SMC reset:

  1. The computer’s fans are running at high speed, even though it does not have a lot of applications open, and is properly ventilated.
  2. The keyboard backlight appears to behave incorrectly.
  3. The Status Indicator Light (SIL) appears to malfunction.
  4. Battery indicator lights, if present, appear to behave incorrectly.
  5. The display backlight doesn’t respond correctly to ambient light changes.
  6. The Power button does not seem to work.
  7. Closing or opening the lid of a Mac does not make the computer go to sleep or wake up.
  8. The computer sleeps or shuts down unexpectedly.
  9. The battery does not appear to be charging properly.
  10. The MagSafe power adaptor LED doesn’t appear to indicate the correct activity.
  11. The computer is running unusually slowly although it is not experiencing abnormally high CPU utilization.
  12. Applications are  malfunctioning, or not responding after being opened.

Here is how to do a SMC reset with Intel-based Macs:

  1. Shut down the Mac.
  2. Connect your computer to an external power source.
  3. Press the Shift-Control-Option keys and the Power button together.
  4. Press the Power button to turn the computer back on.

Note: Do not reset the SMC arbitrarily. Try force quitting any application that may have become unresponsive, and/or restarting the machine first.

[Image courtesy: Apple]