Will my old hard drive work in a new identical Mac mini?

The approach I would use would be to remove the drive from the old enclosure and either put it in a 2.5" USB enclosure or get a USB-to-SATA adapter. Then plug that in to the new Mini and verify that the drive is operational and has all your data.

Next, I would proceed to do a new clean install on the new Mini. I boot the new Mini in its current state and log in and then create a new MacOS USB installer on a USB Flash drive with the version of MacOS desired (note: it should be at least the version that you were running on the old Mini or newer):

Create a bootable installer for macOS - Apple Support

Once complete, boot to the USB installer (hold down the option key when rebooting and select the installer). Once the installer loads, select Utilities->DiskUtiliy in the menus. Use it to reformat the internal drive. When complete, go back and start the installer. Let it do its thing and after it installs and reboots it will come to a point where it will ask if you want to migrate from another computer or Time Machine backup. Plug in the old drive to USB and continue following the on screen instructions. At a point you will be prompted with a screen giving you the option of what to migrate. Select all the items you wish to migrate and click continue. This migration part may take some time depending on how big your old drive is and how much is on it. when it is complete, you should have it working nearly exactly as your old Mini.

I strongly suggest this approach as opposed to swapping drives as you don't need to open up the new Mini and possibly damage something in the process.

Tracy Reynolds Said:

"Will my old hard drive work in a new identical Mac mini?: It's dead. It doesn't turn on. There is no power light. I suspect the power supply. If it doesn't turn on how can I create a Time Machine Backup?[...]"

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Thank you for the followup reply.

Troubleshooting Mac mini Power:

Well, you'll never be able create a Time Machine Backup, if you can get it back up and running. So, try troubleshooting the power...

Reset the SMC and your NVRAM:

Try Resetting the SMC and NVRAM, but this time, using an external keyboard. Connect an external monitor and see if you get an output.

A Few Links to Refer to Power:

• If your Mac doesn't Turn On - Apple Support

• How to Turn your Mac On or Off - Apple Support

• If your Mac doesn't Turn On or Start Up - Apple Support

Tracy Reynolds Said:

"Will my old hard drive work in a new identical Mac mini?: My "home computer" died, a Late 2012 mini. I have purchased an identical mini. Will my old hard drive boot the new mini as if it's the old one?"

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Restoring a Recent Mac from an Older Hard Drive:

The only operating system that will install on a Mac is the one that it can preinstalled with and from then on. You cannot install an earlier macOS on it. So, how exactly has it "died"? Is it just not powering on? You only option is to use a hard drive reader, and transfer what need be, or create Time Machine Backup on this older Mac, and then transfer what you can, through use of Migration Assistant. So, how would you define "dead"?

Pull the hard drive from the dead 2012 Mac mini and put it into a 2.5" external drive enclosure or on a USB to SATA adapter. Then plug that into the replacement 2012 Mac mini and access or migrate from the dead Mac mini hard drive.

This will prevent you from having to swap the drives and possible putting a dead hard drive into the replacement Mac mini.

Tracy Reynolds Said:

"If it doesn't turn on, how do I reset the SMC and the NVRAM? It's a Mac mini. ALL keyboards and monitors are external."

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Read the Hard Drive:

Then, you'll need an Apple-Compatible Hard Drive Reader (also known informally as "a toaster". Get one on Amazon: mac hard drive toaster

Tracy Reynolds wrote:

It's hard to believe that a dead hard drive would keep the power light from coming on. Wouldn't the mini try to power up and indicate on the monitor that no OS could be found?

I was only trying to prevent you from having to operate on the replacement Mac mini until have tested the dead Mac mini's HDD.

As BDAqua says, you can startup from the dead Mac mini's HDD externally to see if it is still good.

In the end, swapping drives or starting up externally from the dead is totally up to you.

Personally I have two 2012 model Mac mini's that have been upgraded with SSD. If I was going to operate on the replacement Mac Mini, I would upgrade it to a 2.5" SSD instead of putting the dead Mac mini's HDD into it.

If the migration would transfer my programs as installed I would sleep easier.

Instead of Migration Assistant Carbon Copy Cloner will accomplish that, use Legacy Mode...

http://www.bombich.com/software/ccc.html

Tracy Reynolds wrote:

This has been the best reply to my actual question. My main concern is all my programs that would have to be reinstalled. If the migration would transfer my programs as installed I would sleep easier. ...≥

Migration Assistant during the install processes will restore every thing Apps, data, settings if you select to do so. Done it my self many times over the years for various reasons.

The only possible caveat may be that you may need to re-activate some apps since you are moving to a new machine.

Yes, likely, but simple to try. :)

Besides, you can try booting from it by holding Option key at startup... you also need an external drive for backups!