hardware failures

What does the long beep mean when I try to boot up my iMac?

Apple iMac

Episode 1474

Bob from Alpine, CA

Bob put his iMac to sleep and then when he went to wake it up, he got a "bong" with a blank screen. Leo says that those tones indicates different things depending on the tone. Here's a list. It's possible the backup battery in the computer is dead and needs to be replaced. But it could also be a failed hard drive. It could also be an EFI ROM update is in progress. If you hold down the D key when booting up, you'll go into diagnostic mode. If that doesn't work, then you have a major hardware failure.