IMac – Bypassing AMD Radeon GPU of 27″ iMac (mid 2011) for Target Display Mode purposes

gpuimactarget-display

I have the 27" mid-2011 iMac that was recalled due to an issue with its AMD 6970M card (1GB for me), but in my case it just malfunctioned after 6 years and it's out of warranty and not eligible for any free repair.

In this forum I got the details of how to connect it to a new 2017 MacBook Pro with Touchbar, using TB cable (older) and TB to USB-C adapter. That's all good.

Questions I have:

  1. Will Target Display Mode attempt to use the GPU of the old Mac or use my MBP's GPU?
  2. If I have to use a video card in the iMac, is there some other integrated graphics card on my iMac I can use and how do I disable the faulty AMD one? The AMD one sometimes (or rather most of the time) prevents the iMac from booting and sends it to an endless restart loop or hangs the machine in ever lasting suspension.
  3. Assuming we get past the two above, anyone know of any easy solution so that I don't have to boot the iMac all the way and then use keyboard shortcuts to enable TDM? I actually would like to connect the keyboard and mouse of the old iMac to the new MBP permanently.

Best Answer

Answers to your questions as asked are:

  1. I've seen your model iMacs used in Target Display Mode regardless of the fact the GPU is playing up, so from that perspective you'll be fine.
  2. N/A see 1 above.
  3. Getting past the first two is the easier part, it's getting the iMac to go into TDM that's going to be your issue as you really need to at least have it booted up to the login screen.

For more general info on TDM refer to: Use your iMac as a display with Target Display Mode.

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