display 4k only 30 Hz instead of 60 Hz in high sierra

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Level 3

545 points

display 4k only 30 Hz instead of 60 Hz in high sierra

i use an LG UHD TV as a 4k monitor on my mac pro (late 2013).

i connect via thunderbolt using a mini display to HDMI 2.0 active adapter (club 3D 1170). since apple blocks the native resolution of the TV (4k, ie 2160x3840@60Hz), i use a small program called RDM (retina display menu) which let me choose among more resolutions. 4k@60Hz worked fine on sierra.

after upgrading to high sierra today, RDM only shows 24Hz, 25Hz and 30Hz, the maximum frequency i get for 4k is 30Hz. de- and re-installing RDM does not help. completely removing RDM does not help.

i also notice a decrease in picture quality (slight colour edges and overall softness). most likely this is not true 4k any more but something slightly scaled down. unfortunately, parameters are not shown in the monitor system utility.

i want my crisp 4k@60Hz back!

any ideas? thank you!

Mac Pro, macOS High Sierra (10.13)

Posted on Sep 27, 2017 5:53 AM

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Answer 1

Sep 27, 2017 8:10 AM in response to mdesignffm

mdesignffm wrote:

thanks.

RDM is as is, there have not been any updates for years.

if i cannot make it work, i need an alternative. feel free to suggest one.

"Display Menu" is available for free in the App Store (it does say it offers in-app purchases, but I don't know what extra features that may entail). I have used it in the past. I just downloaded and it works in High Sierra, but of course I can't say if it will suit your needs. Nothing lost in trying, though.

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Answer 2

mdesignffm Author

Level 3

545 points

Oct 2, 2017 8:09 AM in response to Luis Sequeira1

thanks for the advice, luis.

installed display menu. it only switches resolutions, not frequencies. so it still is 4k@30Hz only. wrote an email to the devs, but they did not answer.

tried out switchresX as well, also no success, even when disabling system protection.

this is really annoying - why does apple shut down 60Hz for TVs, i mean, this is a pretty standard thing. and it did work in sierra. stupid.

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