Is it possible to connect 3 external displays (for a total of 4, including the built-in 5K display) to an iMac Retina 5K, 27-inch, 2017? I have the Radeon Pro 580 with 8GB of VRAM.

I do not need the external displays to be high resolution. In fact, all three of them need to connect via VGA using the following resolutions:

  • External displays 1 & 2: 1920x1080
  • External display 3: 1280x720

If necessary the 3rd display could be a different connection type (e.g. DVI) and/or resolution. The specs for external displays 1 & 2 are not negotiable.

I've reviewed this iMac's specs which seem to say only 2 external displays are supported via the two ThunderBolt 3 (USB-C) ports. However in my research about ThunderBolt it seems like it should be possible to run two simple displays off of one port.

  • Sorry to trouble but could you please let me know if you went with the Diamond USB Adapter? There is so much talk about needing Thunderbolt to add more than 1 external monitor. Now, I'm low on the food chain of Apple knowledge, and I bet that I could (and for just $51 might) add a 4th monitor with that product. – rather Jul 28 '17 at 1:42
  • btw: With so much screen real estate, I can't function without 2 magic trackpads. And, there is a way to assign the monitor into which each app opens its files. anyway, sorry to trouble. – rather Jul 28 '17 at 1:45
  • I have not tried your solution yet but I may end up doing so. I have some hoops to jump through on my end first so it will be a while before I can post back. – Twisty Impersonator Jul 28 '17 at 17:55

I have attached 3 external displays to my MacBook circa late 2011. I stumbled across this nifty product:
Diamond USB Multi-Display Adapter

1 monitor is via the MiniDisplay port and 2 are attached to a USB hub (at USB 2.0 speed).

However, on some forum (that I can't even find anymore) someone mentioned this could possibly cause my CPU to overheat. I have used this 3 monitor config for a few days with no problems and I just started monitoring CPU temp.

I suspect that the performance on those USB monitors is awful? I've no idea. I know so little about graphics, I don't even know how to test them for performance...

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.