Apple - Is it possible to use an iMac in Target Display mode with a 2016 MacBook Pro with USB-C?
My 13" 2016 MacBook Pro drives my late 2009 27" iMac's display using a third-party USB-C to Mini DisplayPort adaptor.
Yes. I have gotten this to work with a 15" Touch Bar MacBook Pro (Late 2016) and a 2011 27" iMac. You need the USB-C to Thunderbolt 2 adapter and a Thunderbolt cable. It will not work with a Mini-DisplayPort cable, which is the same physical plug but not the same protocol.
Don't confuse a USB-C / Thunderbolt 3 port with USB only as the new MacBook Pro do have thunderbolt and not simply USB-C. The new MacBook Pro can output to a Mini DisplayPort target display mode compatible Mac with either a cable that connects directly or an adapter to the existing cable you would have used with the Mac.
I would probably go with a USB-C to MiniDisplayport and use the display port over USB-C protocol since that cable is less expensive than a thunderbolt adapter and would also work with a MacBook (non Pro and non Thunderbolt) or other USB only device. There's probably no speed benefit of thunderbolt for this application.
- USB-C to Displayport - $30 or so street price
- Displayport to miniDP adapter - $5 or so street price
If you wanted thunderbolt - then you'd get Apple's Thunderbolt 3 to Thunderbolt 2 adapter - $30 on sale this month and use any standard thunderbolt cable. I used to believe all iMacs that support Target Display mode will take mini display port signal in - but some people report you need thunderbolt for some Macs. I have no reason to doubt them - so be sure you can return a DP cable if you buy one for this. Some iMacs support both thunderbolt as well as mini DP. Not all iMacs with either port support Target Display mode - especially the new 4k and 5k iMacs - they don't support any video input so you would need a software screen sharing solution for them.
- https://support.apple.com/en-us/HT204592 - Use your iMac as a display with Target Display Mode