i tried to download the SmC update, but when I tried to install I got the following message: "This software is not supported on your system." Does someone know what I should do? How is that even possible considering that the update comes from Apple?
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That's because that SMC update isn't designed for your Mac or you installed it in the past. Just follow the steps of "Turning Power Nap on and off" of this article > http://support.apple.com/kb/HT5394?viewlocale=en_US&locale=en_US
If you don't find it, open > Software Update, and install all available updates