iMac 27" 2020 connect 3 external monitors

Hi


I just bought a 27" iMac 2020 and I want to connect 3 external monitors.

I understand there is a 2 monitor limitation by default but I want to know if there is any other way to extend this to use a third external display without having to get an external GPU?


Currently I'm using some Plugable adapters/hub to use usb-c to HDMI, this is working great.

Is there any chance of using either USB-c or USB adapters/converters etc to be able to get another display working?

iMac 27″, macOS 10.15

Posted on Sep 18, 2020 11:20 PM

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Posted on Oct 5, 2020 11:19 PM

Just thought I would update this in case anyone else has a similar issue.

So turns out that the 2x Thunderbolt 3 ports share the same infra and can only support 2 displays.


This is why on a MBP with 4x TB3 ports, if you use ports on either side of the computer, you can run 3 external monitors (probably 4 if you need) as each side can support up to 2 displays each.


I tested this on a MBP and using only one side of the computer has the same result as my iMac (only supports 2 external monitors)



So as suggested above, I went and got some USB 3.0 to HDMI adapters (specifically I got a Wavlink USB to HDMI 4K HD adapter).


So far so good, it works pretty well.

There is an issue where sometimes when the mac goes to sleep, the monitor won't wake back up like the rest, which requires just turning it off and back on and its fine.


Apart from that though, looks as if CPU is running the same and haven't noticed any issues with lag or anything.




13 replies
Question marked as Top-ranking reply

Oct 5, 2020 11:19 PM in response to doz87

Just thought I would update this in case anyone else has a similar issue.

So turns out that the 2x Thunderbolt 3 ports share the same infra and can only support 2 displays.


This is why on a MBP with 4x TB3 ports, if you use ports on either side of the computer, you can run 3 external monitors (probably 4 if you need) as each side can support up to 2 displays each.


I tested this on a MBP and using only one side of the computer has the same result as my iMac (only supports 2 external monitors)



So as suggested above, I went and got some USB 3.0 to HDMI adapters (specifically I got a Wavlink USB to HDMI 4K HD adapter).


So far so good, it works pretty well.

There is an issue where sometimes when the mac goes to sleep, the monitor won't wake back up like the rest, which requires just turning it off and back on and its fine.


Apart from that though, looks as if CPU is running the same and haven't noticed any issues with lag or anything.




Sep 19, 2020 8:10 PM in response to rkaufmann87

I did. I bought a Plugable dock and a Plugable HDMI splitter, but no matter what the configuration I can only get 2 displays working. The third just shows black and "no input"


I've tested the setup on a new MBP 16" and it works fine when using a TB3 port on either side. But I get the same result (only 2 displays) if I plug both into one side.


I've read about this and the reason behind it, but obviously the iMac only has 2 TB3 ports and they obviously share the same internals

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iMac 27" 2020 connect 3 external monitors

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