iMac (Mid 2007) and later models: About new startup tones
Summary
iMac (Mid 2007) and later model iMac computers, unlike other Macintosh computers, do not use the power LED to indicate there is an issue. iMac (Mid 2007) and later model iMac computers use tones instead.
Products Affected
iMac (20-inch, Mid 2007), iMac (24-inch Mid 2007), MacBook Pro (15-inch, Mid 2009), iMac (20-inch, Mid 2009), iMac (21.5-inch, Late 2009), iMac (27-inch, Late 2009), iMac (24-inch, Early 2009), iMac (20-inch, Early 2009), iMac (24-inch, Early 2008), iMac (20-inch, Early 2008)
The following table lists the new tones and their meaning:
| Tone(s) | Description |
| 1 tone, a 5-second pause, repeat | No RAM installed |
| 3 successive tones, a 5-second pause, 3 successive tones | RAM does not pass data integrity check |
| 1 long tone when holding down the power button | Firmware upgrade in process. See About firmware updates for Intel-based Macs for more details. |
| 3 long tones, 3 short tones, 3 long tones | Firmware restoration from CD in process. See About the Firmware Restoration CD (Intel-based Macs) for more details. |
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