OK, so has no one cracked it yet? The internet has nothing. This is model specific so we're only talking about this one model. In the 2011 iMac running Lion, the chime is apparently part of the "BIOS" not the OSX. So many common workarounds don't work. Things that DO NOT WORK: Startupsound.preffane Muting the sound before shutdown Holding mute on startup The appleScript volume hack Setting the volume to off or low before shutdown Setting the volume to off or low in system preferences So, has anyone managed to stop their 2011 iMac (running Lion) from making a startup sound? PS. This discussion applies ONLY TO THE 2011 iMac series, only when running Lion, so no speculative ideas necessary, and please no debates about how we should like the sound or never restart or whatever.