When to reset SMC

Reasons SMC may need reset

The following symptoms might mean that an SMC reset is necessary:

• Computer's fans run at high speed, even though it isn't under heavy usage and is properly ventilated.

• The keyboard backlight behaves incorrectly.

• The status indicator light, if present, behaves incorrectly.

• Battery indicator lights, if present, behave incorrectly on Mac notebooks with a non-removable battery.

• The display backlight doesn't respond correctly to ambient light changes.

• Mac doesn't respond when you press the power button.

• Mac notebook doesn't respond properly when you close or open the lid.

• Mac sleeps or shuts down unexpectedly and you can't turn it back on.

• The battery doesn't charge properly.

• MacBook or MacBook Pro doesn't charge through its built-in USB-C port.

• MacBook or MacBook Pro doesn't recognize external devices that are connected to its built-in USB-C port.

• The MagSafe power adapter LED, if present, doesn't indicate the correct charging activity.

• Mac performs unusually slowly, even though its CPU isn't under an abnormally heavy load

• A Mac that supports target display mode doesn't switch into or out of target display mode as expected, or it switches into or out of target display mode at unexpected times.

• The illumination around the I/O ports on a Mac Pro (Late 2013) doesn't turn on when you move the computer.How to reset SMC on Macs

How to reset the SMC on Macs

1. Click on the Apple menu, then select Shut Down

2. Connect the AC power adapter

3. After the Mac shuts down, press and hold Shift + Control + Option on the left side of the built-in keyboard, then press and hold the power button at the same time. Hold these keys for 10 seconds
   
   

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4. Release all keys.

5. Press the power button again to turn on the Mac