2017 iMac doesn’t see extra display

[seclusion]

Good evening.
So I had to replace my 2010 Mac Pro and settled on a 2017 27” iMac
I went with the i7, 32 gigs of ram and the 1TB SSD model to be used in my recording studio.

Very nice machine, I await delivery of the OWC 3 dock so I can have everything connected.
I also have a new USB-C to Thunderbolt adapter from Apple.
Also a mini-display to HDMI I used with my Dead Mac Pro.
It all plugs in but when I goto system preferences and hold the option key and press detect displays, the extra monitor isn’t detected. I reseated everything. Tried the HDMI and monitor to my Apple TV and it works.

 

[curmudgeonette]

I also have a new USB-C to Thunderbolt adapter from Apple.

That adapter is only for Thunderbolt devices. It is NOT a USB-C to DisplayPort adapter.

You don't say what type of monitor you have. If you have a DisplayPort monitor, then you need a USB-C DisplayPort Alternate Mode to DisplayPort/MiniDisplayPort cable. There is no Apple branded cable like this - you'll have to pick a different brand.

 

[seclusion]

Thanks, it’s a dell monitor, it’s doesnt have display port, hdmi, vga and dvi.
I have ordered the OWC dock 3. I’ll wait till it comes.
What a nice machine!