When I make the ⌘ Cmd+⌥ Opt+P+R it shows a dialog with lock symbol and to proceed I have to give the password but this way I'm not able to proceed with the resetting of the PRAM. How can I reset the PRAM with this kind of obstacle?

I have a 2008 iMac with Yosemite.


You can also from the terminal in Yosemite run:

sudo nvram -c

and then restart the computer.

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  • I'm curious, Tron - I've been searching for hours and hours and your is the only reference I've been able to find on this - everyone else online seems to only recommend the "take out some RAM" method - where did you discover this and why the heck isn't it more widely distributed? For my part, I'll start linking to your answer to help increase awareness and thank you for sharing this! – Bryan 'BJ' Hoffpauir Jr. Aug 9 '15 at 20:48

This means that a Firmware Password has been set on that Mac. A simple way to disable this is to remove some RAM and restart. Shutdown, replace the RAM, and the Firmware Password will be disabled.

This is the Firmware Password prompt:

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Most modern machines don't have removable RAM so the often mentioned approach of removing RAM will not work on them. However the terminal command sudo nvram -c will.

You can use the Recovery Partition to remove the firmware password if you know what the password is.

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