03-09-2016, 02:34 PM
https://support.apple.com/en-us/HT202768
1 tone, repeating every 5 seconds: This indicates no RAM is installed.
3 successive tones, a 5 second pause (repeating): This indicates RAM does not pass a data integrity check.
1 long tone while holding down the power button: Indicates an EFI ROM update is in progress on a computer manufactured before 2012.
3 long tones, 3 short tones, 3 long tones: Indicates EFI ROM corruption is detected and the computer is in EFI ROM recovery mode.
1 tone, repeating every 5 seconds: This indicates no RAM is installed.
3 successive tones, a 5 second pause (repeating): This indicates RAM does not pass a data integrity check.
1 long tone while holding down the power button: Indicates an EFI ROM update is in progress on a computer manufactured before 2012.
3 long tones, 3 short tones, 3 long tones: Indicates EFI ROM corruption is detected and the computer is in EFI ROM recovery mode.