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A07570 Author

Level 1

61 points

LG Display 72Hz Refresh

Hello--

I have a MacBook Pro 14 -- M1 Pro based from late 2021 -- running macOS 12.5.1. I'm also using an LG Ultrawide 40WP95C-W as an external monitor, it's connected via the LG supplied ThunderBolt 4 cable (USB-C <--> USB-C).

macOS recognizes the monitor and thankfully sets the resolution properly (5120x2160) -- without scaling! Overall the monitor works well and looks good, but I cannot get macOS to offer me the 71 Hz refresh rate the monitor is capable of (see attached).

How can I get my MacBook / LG Ultrawide to achieve a 71Hz refresh rate?

Thanks for your help!

Pertinent Monitor Specs

Refresh Rate: 71Hz
Maximum Resolution: 5120 x 2160
Native Resolution: 5120 x 2880 (5K)
Response Time: 5 milliseconds
Panel Type: IPS

Posted on Aug 23, 2022 3:09 PM

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A07570 Author

Level 1

61 points

Posted on Aug 25, 2022 4:20 PM

So it turns out not to be too difficult of an issue to resolve. As mentioned this monitor has a Thunderbolt 4 / USB-C port as its recommended / best performance connection, I am using that with the LG supplied TB4 cable from my MBP14. However the monitor also provides a 'bus' function, and has a second USB-C port to connect a second monitor or other TB device. I'm using it to drive a Santechi TB4 Doc (which is excellent in capabilities and performance), and turned on a monitor feature called "Thunderbolt Out" which I assumed enabled this port.

Through help from a user on Reddit, I learned that turning off Thunderbolt Out allows for 72 Hz refresh to work. Indeed after turning off TB Out, a 72 Hz option appeared in the Display settings. So anyone with this LG Ultrawide should be aware of this feature if they want the fastest refresh. Interestingly, turning off TB Out does not disable the port, USB and Ethernet continue to function, I just won't be able to plug another Thunderbolt device into the Santechi (though I envision a cabling change that should allow that).

Solved!

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LG Display 72Hz Refresh

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