iMac 2007: migrating old HD's contents to another identical machine?

[Riku7]

My old '07 iMac freezes instantly on startup and I have confirmed that it's not the hard disk nor the RAM, so I'm gonna sell it as spare parts. One day I happened to come by a very cheap identical one and decided to take it. I have taken out the old machine's hard disk: because the machine freezes instantly, I thought that it probably couldn't be used for directly migrating from. I know I _could_ similarly just open up the new iMac now and put that disk in, but seriously, I'd rather not: It's a very stressful and tedious operation. It should be possible to copy the contents of a hard disk onto the new iMac's internal disk, right? I'm just not entirely sure how.

My first idea was to put the old disk into my MacPro5,1 clone it onto an external USB hard disk, and then transfer that clone onto the new iMac. But I realized that I don't have a spare external hard disk big enough to do that! I'll ask around if I can borrow one, but we'll see.

Another idea is to use an adapter (what kind, and are they expensive?) to directly plug the old disk into the new iMac as you would an external disk, and migrate.

Third idea is a combination of the two: putting the old disk into the Mac Pro, connecting the iMac to the same machine (how?) and (somehow in a way I can't imagine) clone the contents of that disk onto the iMac's internal one. I have no idea if this is possible, I'm just imagining here.

What are my options?

Also, the old hard disk as it is: the whole operating system. It's _not_ a Time Machine backup. Is that an issue for migrating?

 

[Fishrrman]

Do you have the hard drive (from the OLD iMac) outside and "in your hand"?

Do you have the replacement iMac on the table and ready to go?

Then... what you need is a USB3/SATA docking station.
These are cheap and plentiful... go online and check them out.
A USB3 version should be backward-compatible with a 2007 iMac.

Then...
Put the drive in the dock.
Connect the dock to the replacement iMac.
Press the power-on button and IMMEDIATELY hold down the option key and KEEP HOLDING IT DOWN until the startup manager appears.
Do you see the icon for the OLD drive (in the dock), in startup manager?
OK, then click it with the pointer and hit return.

Moment of truth -- does the iMac boot from the drive in the dock?
If it does, you can download an older version of CarbonCopyCloner (FREE) and use that to clone the drive in the dock to the drive in the replacement iMac.

 

[Riku7]

Do you have the hard drive (from the OLD iMac) outside and "in your hand"?

Yes, I have taken it out of the old iMac, but I've put it into my MacPro because it has plenty of slots for disks and I wanted to browse the disk's contents. I have a Firewire cable so do I really need to purchase anything more?

 

[Fishrrman]

Does the replacement iMac do "firewire target disk mode"?

If it does, I'd try this:
1. connect replacement iMac to Mac Pro with firewire cable (both powered off)
2. Boot up the Mac Pro, get to the finder
3. boot the iMac while holding down the "T" key to invoke target disk mode
4. if the icon for the iMac drive appears on the Mac Pro's desktop, do this:
5. launch disk utility and erase the replacement iMac drive (Mac OS extended with journaling enabled)
6. once iMac drive is erased, empty, and "waiting"...
7. launch the appropriate version of CarbonCopyCloner
8. use CCC to clone the contents of the OLD iMac drive to the replacement iMac drive.
9. when done, shut down, disconnect, and see if the iMac will boot up

 

[Riku7]

I don't understand – the machine that appeared fine when I tested with El Capitan exhibits exactly the same issues as my old dead iMac 2007 when installing Leopard from a disc: Freezes at account setup, and the more times you start over, it freezes at an earlier stage. When I let the computer cool down, I manage to just about do the account, but then it freezes when the desktop is only almost loaded. I don't understand: Why wouldn't the machine work with an OS that's from the same era? Now I've seen not one but two iMac 2007s that have this same thing going on. Do they have a history of just being unsolvable? Because back when it was my main machine, I don't remember any particular freezing.