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iMac Pro 4k 60Hz External Monitor

Hello,


I have an entry level 2017 iMac Pro running Mojave 10.14.6 which is connected to

an Apple USB-C to HDMI adapter, which is connected to

an AmazonBasics 15ft Premium HDMI cable (18Gbps) which is connected to

a 2018 Vizio P-Series 55" screen


Despite the fact that each link in that chain supports 4k at 60Hz, when I check the system information on the iMac Pro, it shows that I'm only displaying at 30Hz:



What's going on here? What am I missing?



iMac Pro, macOS 10.14

Posted on Jul 12, 2021 2:18 PM

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Question marked as Top-ranking reply

Posted on Jul 14, 2021 4:06 PM

Unsurprisingly, Apple tech support was in no way helpful.


I did find this thread which was helpful. I downloaded EasyRes, which allows you to chose between ALL of the display options/refresh options for a given display. Now my display is running 3840x2160 at a 60Hz refresh rate. Solved.

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4 replies

Jul 13, 2021 3:46 PM in response to JCorHelps

Display preferences aren't any help. There's no option in display preferences to change the display's refresh rate (even when I option-click "scaled" on the second monitor's settings box).


Unfortunately I do not have another 55" 4k monitor handy. I have tested with other cables, as well as other adapters, all rated for 4k 60Hz. No luck with any of them.

iMac Pro 4k 60Hz External Monitor

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