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Resetting your Mac’s System Management Controller (SMC)

By Macologist Erik R. posted on June 25th, 2010

The other day someone brought in a unibody 13″ MacBook Pro with a noisy problem. Rather than the standard RAM tones (which is part of a standard self-test) this person’s MacBook Pro continuously beeped.

After checking for battery issues, it became clear that this issue may be resolved with an SMC reset.

SMC stands for “system management controller” and this little guy is responsible for many low-level functions on Intel-based Macs, such as responding when you press the power button, responding when you open and close the lid of your laptop, and sensing changes to ambient lighting.

It’s certainly possible that the SMC could encounter an issue that might cause strange behavior – much like the situation described above with the continuous beep. In these odd cases, resetting the SMC may be the only way to resolve an issue, however, an SMC reset should only be attempted after all other tried and true troubleshooting have been performed. If you’re at all uncomfortable with the proceedure feel free to make an appointment with our HelpDesk folks – that’s why we’re here.

Before You Reset Your SMC

• Try each of the following steps in the order below before you reset the SMC. Make sure to test that the issue remains after completing each troubleshooting step.

• Press Command + Option + Escape to force quit any application that is not responding.

• Put your Mac to sleep by choosing the Apple () menu from the upper-left menu bar and then choosing Sleep. Wake the computer after it has gone to sleep.

• Restart your Mac by by choosing the Apple () menu from the upper-left menu bar and then choosing Restart.

• Shut down your Mac by by choosing the Apple () menu from the upper-left menu bar and then choosing Shut Down.

• If your Mac appears to be running normally but isn’t responding, force the computer to shut down by pressing and holding the power button for 10 seconds. Note: You will lose any unsaved work in any open applications.

For Mac portables experiencing issues related to the MagSafe power adapter and/or battery, try:

• Unplug the MagSafe power adapter from the Mac and the wall power socket for several seconds.

• Shutdown the Mac. Physically remove and re-insert the battery (if it’s removable) and startup the Mac.

• If the issue is still not resolved after following the troubleshooting items above, an SMC reset may be necessary.

• After performing normal troubleshooting, these symptoms may indicate that an SMC reset may be necessary:

Resetting the SMC

The process for resetting your SMC is slightly different for laptops with removable batteries v.s. non-removable, and desktops also have their own process. We’ve outlined the process for each below:

SMC reset for Mac laptops with a removable battery

• Shut down the computer.

• Disconnect the MagSafe power adapter from the computer, if it’s connected.

• Remove the battery.

• Press and hold the power button for 5 seconds.

• Release the power button.

• Reconnect the battery and MagSafe power adapter.

• Press the power button to turn on the computer.

SMC reset for Mac laptops with non-removable batteries

These include MacBook Pro (Early 2009) and later, all models of MacBook Air, and MacBook (Late 2009).

• Shut down the computer.

• Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.

• On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.

• Release all the keys and the power button at the same time.

• Press the power button to turn on the computer. Note: The LED on the MagSafe power adapter doesn’t change states or temporarily turn-off when you reset the SMC.

SMC reset for Mac Pro, Intel-based iMac, Intel-based Mac mini, or Intel-based Xserve

• Shut down the computer.

• Unplug the computer’s power cord.

• Press and hold the power button for 5 seconds.

• Release the power button.

• Attach the computers power cable.

• Press the power button to turn on the computer.

So there you have it, a full breakdown of SMC resets for most late-model Mac computers. The next time your MacBook Pro starts beeping through the night you’ll know where to turn for the answer. :)

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