Power, including the power button and power to the USB ports.Indicators or sensors such as status indicator lights (sleep status, battery charging status, and others), the sudden motion sensor, the ambient light sensor, and keyboard backlighting.Fans and other thermal-management features.Behavior when opening and closing the lid of a notebook computer.If you're experiencing issues related to any of the following, it's time to reset your SMC: The System Management Controller (SMC) is related more closely to power management and hardware issues, especially on MacBooks. Learn more about PRAM from Apple support. Otherwise, release the keys after the Apple logo appears and disappears a second time. If your Mac plays a startup sound, release the keys after the startup sound chimes a second time.Immediately press and hold the following four keys together:, ,,.Turn it back on by pressing and releasing the power button.To reset your Mac's PRAM, do the following: Generally, I always reset the PRAM as the first troubleshooting step.

Wireless networks randomly won't appear.Serial Port Configuration and Port definition.Caret blink time (insertion point rate).You should reset your PRAM if you're experiencing problems related to any of the following: PRAM (Parameter RAM) is a type of RAM that is used by your Mac to store certain settings and access them quickly.

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