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User profile for user: miaofromlisboa
miaofromlisboa Author
User level: Level 1
5 points

Can iMac 2017 5K 27' support 3 external monitors?

Does anyone know if the 2017 5K 27' iMac can support 3 external monitors?

Mine is with Radeon Pro 580 8GB graphics, and can't make it work with 3 external monitors.


My setup:

  • 2 x 1080p 24' HP monitors connected with hdmi cables to a thunderbolt 3 hub which is connected to 1 of the 2 thunderbolt port in my iMac
  • 1 x LG ultrawide 29 connected with a USB C to HDMI cable to the other thunderbolt 3 port


The hub, cables and monitors are all working fine. However the 3 external monitors can't be used simultaneously, only 2 can be supported each time. Tried to disconnect and reconnect all the monitors with different orders, the last one (LG or HP) will always show "No Signal".


Is it because the iMac 2017 can only support up to 2 external monitors due to hardware / graphic limitation? Is there any configuration I can do to make it work?

iMac 27″ 5K, macOS 11.2

Posted on Feb 24, 2021 4:26 AM

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User profile for user: padams35
padams35
User level: Level 4
3,307 points

Posted on Feb 24, 2021 5:04 AM

Hardware limitation. The iMac only has 2x DisplayPort channels routed to Thunderbolt.


Alternatives:

a) Use an Ultra-wide display or a 4K TV in place of two monitors.

b) Try a USB to HDMI adapter (Requires 3rd party software. Make sure any adapter is compatible with your version of MacOS.)

c) Use a 3840x1080 to 2x 1920x1080 or similar video wall device. Matrox makes a variety, but most have DVI output. (Note: not the same as an HDMI splitter which simply duplicates one input to multiple outputs).

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User profile for user: padams35
padams35
User level: Level 4
3,307 points

Feb 24, 2021 5:04 AM in response to miaofromlisboa

Hardware limitation. The iMac only has 2x DisplayPort channels routed to Thunderbolt.


Alternatives:

a) Use an Ultra-wide display or a 4K TV in place of two monitors.

b) Try a USB to HDMI adapter (Requires 3rd party software. Make sure any adapter is compatible with your version of MacOS.)

c) Use a 3840x1080 to 2x 1920x1080 or similar video wall device. Matrox makes a variety, but most have DVI output. (Note: not the same as an HDMI splitter which simply duplicates one input to multiple outputs).

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Can iMac 2017 5K 27' support 3 external monitors?

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