Tones on Starting
Sometimes you'll turn your Mac on and it'll start beeping in a variety of patterns. Here’s a short list of what each beeping pattern means:
- 1 tone repeating every 5 seconds:
When you start your Mac, it will automatically run system diagnostics. If you hear this pattern of beeping, it means that the Mac could not find any RAM installed. Either your computer's memory was removed or something is interfering with the system checkup.
- 3 successive tones followed by a 5-second pause:
This indicates that the Mac found RAM installed, but the memory failed to pass the data integrity check.
- 1 long tone if you hold down the power button:
This indicates that an EFI ROM update is in progress. This only happens on computers manufactured before 2012.
- A successive sequence of 3 long tones, 3 short tones, 3 long tones, etc.:
This means that your computer has detected an EFI ROM corruption and the computer is in EFI ROM recovery mode. Newer models recover automatically from a corrupted ROM. When this occurs, a progress bar appears on the screen during ROM recovery mode. While on this mode, you should not shut down or disturb the computer in any way until it completes the OS X boot.
For all of the tones on boot up we discuss above, you should look into contacting Apple tech support since they all indicate you’re your computer could be in dire need of maintenance.
You can also cause your Mac to produce tones, usually with certain key combinations. These key combinations will initiate some operation upon start-up. These are a few of those combinations:
- Shift ⇧
Start up in safe mode.
- Option ⌥
Launch Startup Manager.
Start up from a bootable CD, DVD, or USB drives.
Start to either Apple Hardware Test or Apple Diagnostics, depending on which Mac you’re using.
Same above, but it will start these programs via the internet.
Start up from a compatible NetBoot server.
Start up from a NetBoot server using the default boot image.
Start up from OS X Recovery.
Same as above, but using the internet.
These are some of the commands available at the start up and they will also produce unique sounds too.
It’s always important to know how to differentiate between user induced sounds and system sounds, as they can indicate a hardware or software failure on your Mac.