New iMac to Boot the Old iMac?

[Azrael9]

Hello fellow Mac luminaries.

I recently bought the flag ship iMac. And yes, it's mighty fine.

My old iMac had a fried 680MX gpu. But everything else on the machine is fine screen/hard drives etc. Just the gpu won't let the Mac boot (thought it can boot into Bootcamp, I noted with irony.)

Someone did suggest if I had another Mac (and now I do...) I could use it's gpu to boot my old iMac.

If true, I'm guessing I need a cable for this? Do I put the old iMac into target mode or something?

Late 2012 iMac 27 inch model. It's so I can get my files of the old machine. But if it could run as a 'back up' iMac for a little while it would have some use, also.

Any help would be appreciated.

Azrael.

 

[chrfr]

Someone did suggest if I had another Mac (and now I do...) I could use it's gpu to boot my old iMac.

There's no hardware compatibility to use a GPU from one iMac in another, remotely or otherwise.
Your old Mac might be functional enough to start up into target disk mode, but you need an expensive cable and adapter. This would allow your old Mac to appear as an external disk drive on the new Mac. To do this you need a Thunderbolt cable and a Thunderbolt 2 to 3 adapter and you connect them between the 2 computers.

Transfer files between two Mac computers using target disk mode

You can connect two Mac computers using a USB, USB-C, or Thunderbolt cable, then transfer files.

support.apple.com

 

[Azrael9]

chrfr,

Thank you for your help.

Appreciated.

Azrael.

 

[Juicy Box]

I second everything @chrfr said, but will add a few things.

In addition to using Target Disk Mode to access files, it is possible to boot your new iMac from the old iMac drives.

If you were using Catalina (the OS your new iMac shipped with) on your old iMac, you could boot your new iMac from the internal drive of your Late 2012 iMac a few different ways.

The easiest would be getting the Apple bidirectional adapter and a Thunderbolt 1 or 2 cable, connecting the two Macs, and boot the Late 2012 iMac while holding the "T" key in. This will boot the iMac into Target Disk Mode, basically turning it into an external drive.

You could also take the internal drive(s) out of your Late 2012 iMac, connect it to your new iMac.

Either method would then require you to hold in the alt/option key during start up on your new iMac. Then select the external drive from your Late 2012 iMac to boot from.

With the new security chip, I think you may need to go into the settings on your new iMac and allow external booting.

My old iMac had a fried 680MX gpu.

How do you know it is the GPU?

 

[chrfr]

I second everything @chrfr said, but will add a few things.

In addition to using Target Disk Mode to access files, it is possible to boot your new iMac from the old iMac drives.

If you were using Catalina (the OS your new iMac shipped with) on your old iMac, you could boot your new iMac from the internal drive of your Late 2012 iMac

The old iMac would have to be on the very newest version of 10.15.6 with the supplemental update in order to boot the 2020 iMac. It is possible to boot to internet recovery and install to the old iMac’s disk once external booting has been allowed on the 2020, but this is a lot of work compared to just copying files from the old one, and performance would be dramatically worse.

 

[Juicy Box]

but this is a lot of work compared to just copying files from the old one

I was under the impression that the OP wanted to boot from the old iMac or the old iMacs boot drive.

If the OP was looking for a method of just copying files to the new Mac, Apple's Migration Assistant would probably be idea in that situation.

Apple's migration assistant would be a lot more thorough than manually moving files over, and could also migrate settings, preferences, profiles, and accounts too.

and performance would be dramatically worse.

Well, yeah it would, but this shouldn't be surprising.

I wasn't thinking that booting from the old iMac was going to be the main booting drive, just when the OP wanted to use the old boot drive.

Either way, if the OP just wanted to copy files over, Apple's Migration assistant would be the way to go. Easy to use, and it will migrate all the files exactly where they need to be.

OP: If that is what you are looking for, doing this would be the same exact way as using the iMac as an external drive using Target Disk Mode, or removing the internal drives and using them externally.

You can use the Migration Assistant app in the Utilities folder:

Transfer to a new Mac with Migration Assistant - Apple Support

Use Migration Assistant to copy your files from another computer.

support.apple.com

 

[Azrael9]

The 1st priority is just to get the data off the internal drive.

The late 2012 won't boot. In any mode. The progress bar gets 'so far' and hangs.

It will in Bootcamp.

How do I know the GPU is fried? Green caterpillar fleck pattern in Windows. (I can boot into Windows Bootcamp in 'safe mode' without any fleck at all.)

I have an external SSD (that had a newer OS on...than the internal drive...) that has 'nearly' up to date data from my project. It couldn't boot the 'fried gpu iMac' either. But? When I attached it to my new iMac? It read the data from my backed up Project on that np. So it's less perilous than it was. But if I can get the 'slightly' newer data' of my internal drive of my old 'friend gpu' iMac...then that would be good to have.

I thought it would be just a matter of attaching a (TB1 to 3? USB?) cable to the old iMac and the new iMac and the newer would see the hard drive of the old iMac just as it did the external SSD when attached? (It works as an external HD np...but it won't boot from it due to security on the new iMac. Will the internal driven on the old iMac...be seen as long as the old iMac is turned on and has power?

Apple migration assistant. Does it migrate over your internet bookmarks? Other than that. I don't have much data outside my project folder. I do have my apps which I could bring over. Affinity, Z-Brush etc. It would save me re-downloading them if I could just copy them across.

Re: the old iMac as an external screen? I was just wondering if it could be powered by the newer iMac's gpu to use as an external screen for more screen real estate? With a monitor cable? TB cable? Or if the gpu could help it boot.

Not something I've done a lot of. So it takes a few times to get my head around it. As I've said, the external SSD could be read as a data hd. I'm hoping the internal one can be too. I'd only need to get a cable? Could the old iMac's USB ports and the newer iMac's USB ports be used? USB or TB1to3 converter?

I've got a local computer shop. I could try getting the cable from them before I order from Amazon.

Musingly.

Thank you for help and the links.

Azrael.

 

[Azrael9]

'T' mode won't boot.

But I got something unusual I haven't got before. A circle with a Lightning Arrow through it and it just moved around the grey screen. Is that Target Mode? Is that letting you know to attach a cable? Looks like a TB port symbol.

Azrael.

 

[Juicy Box]

The already posted support site answers a lot of your questions:

Transfer files between two Mac computers using target disk mode

You can connect two Mac computers using a USB, USB-C, or Thunderbolt cable, then transfer files.

support.apple.com

I thought it would be just a matter of attaching a (TB1 to 3? USB?) cable to the old iMac and the new iMac and the newer would see the hard drive of the old iMac just as it did the external SSD when attached?

Apple's TB2/TB3 bidirectional adapter with a TB cable would work and is fast, but the adapter can be pricey, and if you are just using it for a one time access to retrieve your data, I would consider getting a USB-A to USB-C cable. It isn't nearly as fast as using the bidirectional adapter, but it would probably be the cheapest option.

Apple suggests this one, but you could probably get one cheaper:

mophie USB A Cable with USB C Connector 2 m - Apple

Apple Store Search Results

www.apple.com

Will the internal driven on the old iMac...be seen as long as the old iMac is turned on and has power?

No, the old iMac needs to be in Target Disk Mode. Hold "T" during the boot on the old Mac, essentially turning it into a very large external drive.

Apple migration assistant. Does it migrate over your internet bookmarks?

Yes, all of the data to all of your apps, along with the settings.

It has been a while since I used it, but IIRC, after using the Migration Assistant, it would be like using your old Mac, but on the newer Mac with the newer OS. All of your files and settings would be migrated over.

Re: the old iMac as an external screen? I was just wondering if it could be powered by the newer iMac's gpu to use as an external screen for more screen real estate? With a monitor cable? TB cable?

The Late 2012 27" iMac is capable of Target Display Mode (not to be confused with Target Disk Mode), and can be used as a second display for other Macs with TB1, 2, or 3.

You would use either a TB cable or TB cable with the bidirectional adapter depending on what Mac was used with it.

But, you need to boot the iMac that you want to use as a display, so it wouldn't work in your case unless you were able to get you old iMac to boot.

'T' mode won't boot.

It isn't suppose to.

But I got something unusual I haven't got before. A circle with a Lightning Arrow through it and it just moved around the grey screen. Is that Target Mode? Is that letting you know to attach a cable? Looks like a TB port symbol.

That is Target Display Mode. If you had an appropriate cable, you could connect and get all the data you needed.

 

[Azrael9]

Cheers, Vertical Smile.

You're a diamond geezer (as they say in the UK) for all that info'.

That's made things a lot(!) clearer to me.

Much appreciated!

So, basically, I just need 'that' appropriate cable and put my old iMac into Target Display Mode. And I can get my all my data. Sweet.

Azrael.

 

[Fishrrman]

OP wrote:
"I have an external SSD (that had a newer OS on...than the internal drive...) that has 'nearly' up to date data from my project. It couldn't boot the 'fried gpu iMac' either. But? When I attached it to my new iMac? It read the data from my backed up Project on that np. So it's less perilous than it was. But if I can get the 'slightly' newer data' of my internal drive of my old 'friend gpu' iMac...then that would be good to have."

If you have a relatively recent external backup, USE THAT.

I realize it won't "get everything" you wish.
But... like the old song goes...
"you can't always get what you want
but you can try sometimes
and you might find
you just get what you need."

 

[Azrael9]

S'funny you should say that.

Having a 'fresh' look at my project data (the 'nearly' most recent data from the external SSD.) It made me think.

Simplify. Simplify. Simplify.

Azrael.

 

[Azrael9]

I've got the USB A to USB C cable for my old iMac and attached it to my new iMac. 'A' in the old iMac...and 'C' in my new iMac.

The old iMac is in Target Display Mode (with the floating Lightning symbol...)

I can't see the hard drive from my old iMac on my new iMac.

Thoughts?

Azrael.

 

[Azrael9]

• Target disk mode doesn't support connections that use an Apple USB-C Charge Cable, USB-A to USB-A cable, or Mini DisplayPort
  
  cable.

...

Transfer files between two Mac computers using target disk mode

You can connect two Mac computers using a USB, USB-C, or Thunderbolt cable, then transfer files.

support.apple.com

Could it be that I have a USB-C 'charge' cable and not a data cable? It has A and C ends.

The old iMac's HD is not showing up on the new iMac.

Azrael.

 

[Boyd01]

Does target disk mode work with a USB connection? I was under the impression that it only works on firewire or thunderbolt. If so, you would need an adapter which will be expensive. Then again, I might be wrong.

 

[Azrael9]

I returned the USB A to C cable.

• To connect a USB-C port to a USB-A port, use a USB-A to USB-C cable that supports USB 3.0 or USB 3.1, such as the Mophie USB-A Cable with USB-C Connector.

I tried an A to C cable. Strangely it didn't work.

Maybe if I can try a TB1 to TB3 next.

Azrael.

 

[Juicy Box]

I tried an A to C cable. Strangely it didn't work.

Did you use the one that Apple suggested?

Like I mentioned earlier, some cables may not work, as they need to do two-way data transfer, and many of them are just for charging.

Maybe if I can try a TB1 to TB3 next.

If you didn't already try the USB-A to USB-C cable that Apple suggests using, this would still be the cheapest option.

The TB2 to TB3 bidirectional adapter is $50. After searching for a while, I found one for a little cheaper, but not by much.

Does target disk mode work with a USB connection? I was under the impression that it only works on firewire or thunderbolt.

It works, but only if one of the Macs have TB3/USB-C, and you have to use the correct cable which it sounds like the OP used a charging cable which will not work.

 

[ignatius345]

It has been a while since I used it, but IIRC, after using the Migration Assistant, it would be like using your old Mac, but on the newer Mac with the newer OS. All of your files and settings would be migrated over.

I used Migration Assistant under Catalina to move from an older MacBook to a brand new one a few months ago -- can confirm it works just as described. When it was done, everything from the old Mac was present on the new Mac. Apps, files, system settings, applications preferences. A few applications got cranky about the move (Adobe Creative Cloud, a couple others), but otherwise it was seamless.

 

[Azrael9]

Did you use the one that Apple suggested?

Like I mentioned earlier, some cables may not work, as they need to do two-way data transfer, and many of them are just for charging.


If you didn't already try the USB-A to USB-C cable that Apple suggests using, this would still be the cheapest option.

The TB2 to TB3 bidirectional adapter is $50. After searching for a while, I found one for a little cheaper, but not by much.



It works, but only if one of the Macs have TB3/USB-C, and you have to use the correct cable which it sounds like the OP used a charging cable which will not work.

Thank you for the sage advice, Vertical.

I didn't get the one Apple was suggesting. (That will teach me...). I got one from a local computer shop. And? I'm pretty sure it was a 'charging cable'. And you're right. That's why it didn't work.

Ergo no 'two way data transfer.' And the price of £3.99 suggested this may be the case. . (I walked into that door...)

So, I'll get the Apple recommended cable. And try it properly. Right tool for the right job.

Azrael.