If your Mac beeps during startup

Certain conditions related to memory or firmware may cause your Mac to beep once or more during startup.

On some Mac models, you may hear one of these beep sequences at the beginning of the startup process, while the screen is still blank. These are not the same as the startup sound (chime)

One beep every five seconds

Your Mac isn't detecting any memory (RAM). If you've added or replaced memory recently, make sure it's installed correctly.

Three beeps, then a five-second pause, repeating

The memory in your Mac didn't pass an integrity check. If you've added or replaced memory, make sure it's installed correctly.

Three long beeps, three short beeps, then three long beeps

To resolve a firmware issue, your Mac is restoring its firmware. You may see a progress bar, after which your Mac should start up normally.