Late 2017 iMac firmware password appears after RAM swap

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Level 1

8 points

Late 2017 iMac firmware password appears after RAM swap

Hi all,

I have a strange issue with a Late 2017 iMac that I own.

The original problem was that the iMac would start normally, show the Apple logo and progress bar, but the bar would stop roughly halfway and the Mac would never finish booting.

While troubleshooting, I swapped a RAM module with one from another identical iMac that I had purchased second-hand. I already knew that the second-hand iMac had a firmware password enabled.

After swapping the RAM, my original iMac suddenly started showing the firmware-password padlock whenever I tried to enter Recovery Mode or use the Option startup menu.

I am certain that I never set a firmware password on my original iMac, and I had previously used Recovery Mode on this machine without ever being asked for one.

I have since put the RAM back, but the firmware-password prompt remains.

To make the situation stranger, both iMacs now show the firmware-password padlock when attempting Recovery/Option startup.

I understand that a firmware password should be stored in the Mac’s firmware/EFI and should not be stored on or transferred by a RAM module. However, the appearance of the lock on my original iMac coincided directly with swapping the RAM between these two machines.

Has anyone encountered this behaviour on a 2017 Intel iMac?

Could changing the installed RAM configuration trigger some previously stored EFI/firmware-password state, or is there another explanation for why a Mac that previously entered Recovery without a firmware password would suddenly begin requesting one after a RAM swap?

I have searched extensively but haven’t found another report describing this exact situation.

Thanks for any technical insight.

Posted on Oct 3, 2026 4:38 PM

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Answer 1

Oct 4, 2026 6:30 PM in response to ck.gemka

First.....a sudden performance issue is usually caused by a failing internal Hard Drive, or an issue with third party software. Slightly less likely is file system corruption. All of these are consistent with a failing internal Hard Drive.

Second.....as for the firmware lock, if you don't know the password, then you will need to have acceptable proof of purchase & acceptable personal ID to provide to Apple so that Apple can remove the firmware lock. You will likely need to take the iMac to an Apple Store or an Apple Authorized Service Provider. And more than likely they may say the system is no longer supported as that occurred with me when I tried to have Apple remove a lock on an older system for my organization.....Apple eventually caved & unlocked it after some persuading and of course providing the necessary & acceptable proof of purchase.

Set a firmware password on your Mac - Apple Support

Memory has nothing to do with enabling a firmware lock although years ago, changing the amount of memory in the system would result in the removal of the firmware lock......Apple updated the system firmware to remove this egregious bug.

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Answer 2

kaz-k

Level 9

53,304 points

Oct 4, 2026 6:38 PM in response to ck.gemka

Hi,

I haven't faced such situation, though you'd better contact Apple Support and ask about the issue you face with.

Did you try boot in Safe Mode, by the way?

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