Resetting the SMC can resolve some computer issues such as not starting up, not displaying video, sleep issues, fan noise issues, and so forth.
The System Management Controller (SMC) is a chip on the logic board that controls all power functions for your computer. If your computer is experiencing any power issue, resetting the SMC may resolve it.
The SMC controls several functions, including:
– Telling the computer when to turn on, turn off, sleep, wake, idle, and so forth.
– Handling system resets from various commands.
– Controlling the fans.
Note that resetting the SMC does not reset the PRAM. Resetting the SMC will not resolve issues in which your computer is unresponsive – in these situations, restarting your computer will generally suffice. If your computer exhibits these types of issues after you’ve restarted the computer, try resetting the SMC.
Resetting the SMC on Mac portables with a battery you can remove
Step 1. Shut down the computer.
Step 2. Disconnect the MagSafe power adapter from the computer, if it’s connected.
Step 3. Remove the battery.
Step 4. Press and hold the power button for 5 seconds.
Step 5. Release the power button.
Step 6. Reconnect the battery and MagSafe power adapter.
Step 7. Press the power button to turn on the computer.