So that adapter wouldn't be useful for connecting your ViewSonic monitor.Sorry. Note that Apple's Thunderbolt 2 adapter doesn't provide the DisplayPort signal that you would normally find on a built-in Thunderbolt 2 port. There might be others, but those are the ones I've heard about. Apple, StarTech, and Akito have Thunderbolt 3 to Thunderbolt 2 adapters. That display needs a Thunderbolt input signal. USB-C to MiniDisplayPort adapters (like the ones your Viewsonic VP2780-4K needs) will not work with the Thunderbolt Display. The old Apple Thunderbolt Display all agree will not be supported by the new iMac until new firmware is installed in the adapters. There was a similar HDMI 2.0 adapter with pretty much the same resolution limit and compatibility claims. The description of another adapter (from some company called Plugable) said that it was 'Compatible with 2017 iMac/iMac Pro' ('Adapter has been fully tested for functionality on the 2017 iMac/iMac Pro'). I looked at the description of one (of many, many) USB-C to mDP adapters on Amazon, and it said 'NOTICE: the firmware of our products is updating now, please don’t connect this product to iMac 2017 and MacBook 2017.' The adaptor companies saying that they are not aware of problems.ĭepends on the company. With respect to the audio problem, have you tried going into the Sound preferences and changing the sound output device? If that worked, did it stick across reboots? After 4 adaptors and 2 cables, connecting the iMac to the monitor as a second monitor stops the audio, and slows the iMac down too much.

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