Possibility to use crashed iMac as second display for new iMac?

Hi All,

I have a little tricky technical question and hope someone can maybe help me with this or has experience, here some background information first:

I have a late 2012 iMac 27 inch with 3TB fusion drive, basically the first model with the thin screen design. Unfortunately this iMac crashed last week, meaning it suddely did not start anymore. I have sort of tried everything possible and it is starting in recovery mode but I am unfortunately not able to do anything in there.It appears that parts of the fusion drive are dmamaged but according to disc utility some parts of the disc are still ok, I suspect that the SSD part is still working. Anyway I tried resorting form time machine backup which didnt work, it stopped because obviously the disc is corrupted. I also tried to repair the disc but nothing is happening and I tried to re-install OS X from recovery mode but that is also not possible becauase I am not able to select a disc for installation.
So this is the status, I have an old 2012 iMac which is only startin gin recovery right now.

Anyway I know this would happen at some point, I just wanted to wait a little in case there is coming a new model but now I had no choice and have already ordered a new 27 inch 5K imac.

So basically my question is, will I be able to use my old iMac somehow as a second display for the new imac?
I really wanted to use this opportunity whne I buy a new iMac to be able to use the old as second display so what do I need on my old mac in order to make this work, does it need a functioning OSX installed to be able to use it or not? Would there maybe be any way to instal a "simple" or old system on the still working SSD part of the fusion drive? Or is it maybe even possible to just have it running in recovery mode and it will function as second display, I dont know what the requirements are for this to work?


It would be great to get some help with this.

Regards,
Tom

Why not repair the 2012 iMac? If it's the Fusion drive that failed, you can replace it with a SSD or another Fusion drive. I'm not sure what it would cost (assuming you don't want to do the repairs yourself) but you can always ask around and get some estimates. Since the 2012 is no longer in warranty, you can have it repaired at any authorized Mac dealer who does repairs or at an Apple Store.

I don't believe you can use the 2012 as a second display for the new iMac. Retina iMacs are not supported for Target Display Mode.

Hi and thanks for your answer.

I had anyway the plan to switch to a new one sooner or later, had a lready a serious system collaps when I tried to install mojave.

Oh, I thought it was possible to use it as second display since you can, why does it work with other external displays then?

Regards,
Tom

Having the computer accept a second display is possible because the Mac is capable of sending a video signal outbound to the display. The important thing is that the second monitor can accept that signal as an input.

In the case using a second Mac as a monitor the second Mac has to have the ability to accept the signal. In short it has to have video input capabilities.


Sent from my iPad using Mac-Forums

Oh, I thought it was possible to use it as second display since you can, why does it work with other external displays then?

Click to expand...

You can't because your new iMac does not support Target Display mode.

Please see the following Apple article: https://support.apple.com/en-us/HT204592

Thanks again for your answers, I thought until now that this would theoretically work with my setup if I get a new 5K 27 inch iMac because my late 2012 iMac is in the list of suitable displays that can be used and I was of the opinion that this
"iMac (Retina 5K, 27-inch, Late 2014) and later iMac models can't be used as Target Display Mode displays." means that these models cannot be used as displays as it says "cannot be used as target display mode displays" but I thought of course that these can be used as main imac display but not as second???

maybe I am wrong but thats how I understood it

Regards,
Tom

You can certainly try it out to see if it works for you; nothing ventured, nothing gained, as the saying goes. However, my understanding is that the new (2017) 27" iMac will not support it either way. Another thing to think about is your older iMac will have to be powered up in order to use it as a display. With a defective hard drive in it, it may not function properly even as an extra display.

Yes I can try it of course, would be interesting anyway.

I know it needs to be powered up but I thought it might maybe work in recovery mode, it seems the SSD part of the drive disk is still working

Regards,
Tom