How to disable the ultra annoying Startup Sound on Mac OS X

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Yosemite

I passionately *H*A*T*E* the startup chime that my Mac makes when I switch it on. At least on my MacBook, if the volume is turned down before I shutdown, the system restarts silently. I guess it’s somehow linked to the internal speakers.

Sadly on my Mac Mini this approach doesn’t work: due to the lack of “real” internal speakers , the Mini always wakes up with that horrible eighties K-DONNNNNNNNG noise, waking up my wife and large parts of the neighbourhood.

But there’s good news: thanks to the nvram command we can set a firmware value to suppress this sound. Here’s how:

sudo nvram SystemAudioVolume=%80

This will write a value of 128 (or 80 in hex) to the BIOS. Make sure to shutdown your system and then power back on to “hear” the effect on a Mac Mini: simply restarting it will not suppress the sound, but a full shutdown and restart will do the trick from now on. Result!

As much as I dislike the sound, it is there for a reason: it signals the successful completion of a quick self test. I appreciate this – so I may not want to switch K-DONNNNNNNNG off forever.

It’s easy to remove that value again from the BIOS, using the -d parameter of the same command:

sudo nvram -d SystemAudioVolume

There. Now the horror chime is enabled again, ready to annoy more neighbours at 3am.

Kudos to the following sources:

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