That Mac will ONLY support 1 external display.
If you want additional external monitors you have to use DisplayLink software and a USB-to-HDMI (or DisplayPort, or DVI, etc...) adapter. The DisplayLink website has points to adapter vendors.
@datafornothinandbitsforfree That is correct, that is why I had the link to the Startech displayport adapter in the post.
I have a 32" DELL 4K (U3219Q) that I like, but it takes its own USB-C (NOT Thunderbolt 3) cable, or HDMI or DisplayPort. As it is, I scale it down so everything is not too small.
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I'm a software developer, so I spend most of my time using iTerm2 terminal emulator ssh'ed into remote Linux systems at work.
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One of the things I dislike is I have not found a longer USB-C cable that will work with it, and I've spent a moderate amount trying. That is my biggest dislike.
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My likes, are the size,
lots of screen real estate.
The 4K gives it great resolution, even scaled down.
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For me the color is fine, but I write software, so mostly I look at colorized source code. Not at all the same as video or photo work where getting the colors correct and accurate is important. Slightly different shades of green, blue, red, cyan, etc... in my source code will not bother me.
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This monitor has a built-in KVM, so I can connect 2 Macs to the monitor. I also connect my keyboard and my Magic Trackpad via USB cables to the monitor, so when I switch to the other Mac, the keyboard and trackpad go with the monitor. One Mac uses the DELL provided short USB-C cable, and the other Mac uses an HDMI cable and a USB-A-to-B cable. Somewhat of a hack, but it works.
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If you have the chance, go into a computer store (Best Buy, Staples, other), and actually look at monitors to see if you like what you see. You might even be able to bring your Mac and some cables into the store to see how it looks. Ask the store before you take any of your own equipment into the store.
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Keep in mind if you get 2 identical monitors, sometimes the monitors do not provide sufficient unique identification such that the Mac will know which is the left and which is the right monitor. So after waking from sleep or rebooting, they may switch orientation. We see that sometimes at work (well I see it reported in the company Slack channel).
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There are also users That like the ultra-wide monitors that effectively give you the real estate of 2 monitors in 1 curved display.
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Most of the users at work are either writing software, or using the Macs for business stuff. Very few are involved in video or photo work (they then to get very picky about things the rest of us do not care all that much about).