Make your desktop Mac start up by itself after a power cut

Why it happens

When the power suddenly goes, a desktop Mac switches off and normally waits for someone to press the power button. That's a problem for a Mac mini used as a home server or an office Mac you reach remotely. This switch tells it to start up on its own as soon as power returns. MacBooks don't have it, because their battery keeps them running through a power cut.

How to fix it

1. Open the Apple menu and choose System Settings. Click Energy in the sidebar. You'll find it on an iMac, Mac mini, Mac Studio or Mac Pro.

2. Turn on Start up automatically after a power failure. It takes effect straight away, with no restart needed.

   Energy›Start up automatically after a power failure

3. If you reach this Mac from elsewhere, also turn on Wake for network access in the same pane so it can wake when you connect.

   Energy›Wake for network access

4. For a Mac that must stay reachable, turn on Prevent automatic sleeping when the display is off too.

   Energy›Prevent automatic sleeping when the display is off

Still not fixed?

1. If FileVault is on, your Mac starts up but stops at the login screen until someone types the password. Apps and sharing services don't run until then, so plan for that on a Mac you use remotely.

2. Check the socket really comes back. Some power strips, smart plugs and surge protectors stay off after a cut until you press their button.

3. A small battery backup, often called a UPS, keeps the Mac running through short cuts and gives it time to shut down safely in long ones. That protects your files as well.

4. If the switch is greyed out, the Mac may be managed by a school or company. Ask whoever looks after it.

5. If the Mac won't start even when you press the power button after power returns, the power supply may be faulty. That's hardware, so contact Apple Support or an Apple Authorized Service Provider.