Using iMac in Target Display Mode with a MacBook Pro
I don’t know if it’ll work with the Mini DisplayPort. I was stuck in a nasty half boot to grey screen problem last November on my 2011 27” iMac. While I was troubleshooting I tried the mini display port and tried TDM but it didn’t work. So I bought a Thunderbolt cable and then a FireWire cable or vice versa. The Thunderbolt cable worked... but I think the FireWire worked too. Now I’m starting to doubt my memory. I was going the other direction though. iMac TDM on a MBP. I tried the MDP port w/my old 2009 MBP &amp; the 2012 MBP. Neither worked with my iMac. It That was just my experience. It’s worth trying a TB or a FW cable. I just remember the mini display port didn’t work for TDM for me. Which sucked because I had multiple mini display cables/adapters lying around from porting my laptops to the TV but I had a tough time finding the other cables in my town. The only Thunderbolt cable I could buy was super short. That’s how I’m certain that it definitely worked. I had to stack books to get the laptop close enough.   I think I had no choice but to order the FireWire online. Hope you get it to work. :-)