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I have a MacBookPro11,2 connected via HDMI to a 4K television. I would like to try driving the display at various resolutions and frequencies, to see if that might alleviate some problems with signal stability. However the Displays prefpane only offers me a list of "scaled" resolutions, all of which are interpolated up to 4K, meaning the HDMI signal and monitor are still operating at 4K. Is it possible to foce the HDMI output to a specific (lower) resolution/refresh rate?

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  • What resolutions does the TV support?
    – Allan
    Commented Jun 2, 2017 at 0:12
  • Sadly the vendor (Westinghouse) doesn't provide anything approaching technical specs for the display (actually made by Avision Technology Changzhou) model WD50UC4300. It claims the HDMI input supports "Up to 4K" which would suggest it can accept e.g. a 1080-line signal.
    – ruief
    Commented Jun 2, 2017 at 1:52
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    According to the specs it supports everything from 480i to 4K
    – Allan
    Commented Jun 2, 2017 at 2:39

3 Answers 3

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The answer is: Yes, this is possible.

I found a piece of trialware called SetResX that lets you set arbitrary real resolutions on the HDMI output, and it works!

I also found a video tutorial here that explains how to do that yourself with a substantial bit of effort, and without the nice UI, but I haven't tried that method.

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  • SetResX works by modifying a system file. When SIP is enabled, that hack is not possible. If you're ok with not having SIP enabled, then use SetResX.
    – Jari Turkia
    Commented Apr 23, 2020 at 13:03
  • I have SIP enabled and SetResX still works for me.
    – ruief
    Commented Apr 24, 2020 at 18:14
  • Ok. You might not be using custom resolutions. See madrau.com/support/support/srx_1011.html for author's own information. "Beginning with El Capitan, System Integrity Protection does not allow SwitchResX to modify this file."
    – Jari Turkia
    Commented Apr 26, 2020 at 17:14
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Additional answer, to combine with @ruief's answer to use SwitchResX (which I agree works really well, having found it from @ruief's answer and tried it!):

  • Be sure to use a Mini DisplayPort (i.e. thunderbolt) to DisplayPort connector, not an HDMI to HDMI connector - you will likely find a lot more available resolutions; namely, everything that the monitor and MacBook can support which is higher resolution than 1920 x 1080 (aka 1080p)

I am not sure if the above is different between MacBooks? It made a huge difference on my MacBook Pro Retina 13-inch Late 2012; adding genuine resolutions (i.e. as reported by the monitor's OSD, not just scaled displays in other resolutions) up to 2560 x 1600 60Hz - which just weren't there with the HDMI cable.

You might also want to check out this article by Stephen Foskett, which recommends enabling MST-mode on the monitor itself to access even higher resolutions on older MacBooks. However, in my own case I can report that I did not have to enable MST, and that I did eventually get a perfectly usable 4k (3840 x 2160) 27Hz (!) mode (genuinely, as reported by the OSD of the monitor itself) working on my Late 2012 Intel HD Graphics 4000 MacBoo Pro with an ASUS VP28U 4k monitor!!! Definitely no way that could have been achieved without SwitchResX!

Finally, it's also worth noting that another tool, simpler to use than SwitchResX and without the ability to define new modes, but still with the ability to show the 'hidden' resolutions, is RDM which can be installed via a download link from the GitHub page, or via Brew (brew install avibrazil-rdm).

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  • NB If anybody wants to point it out, yes, I'm not 100% answering the question. But I am pointing out that an assumption in the question (that you should use HDMI for this) may be shooting the questioner - and anybody else going down the same road, as I was before - in the foot, since using HDMI is NOT the optimal way to get control over the MacBook Pro's display output!
    – MikeBeaton
    Commented Apr 6, 2020 at 7:54
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According to Apple, connecting your 4K TV to your HDMI port is only supported at either 3840x2160 or 4096x2160 resolutions.

You can use 4K displays and Ultra HD TVs at the following resolutions and refresh rates via the built-in HDMI port of your Mac:

  • 3840x2160 at 30 Hz refresh rate
  • 4096x2160 at 24 Hz refresh rate (mirroring is not supported at this resolution)

Per the specs of your TV, it supports 480i to 4K resolutions on HDMI. It also has PC input (VGA):

Compatible Modes

  • TV Tuner: NTSC/ATSC
  • Component: 480i, 480p, 720p, 1080i, 1080P
  • HDMI: 480i, 576i, 480P, 576P, 720P, 1080i, 1080P, 3840×2160/30Hz, 3840×2160/60Hz
  • PC: SVGA, XGA
  • Optimum Resolution: 3840x2160

If you want to get lower resolutions I recommend connecting to the VGA port on your TV (per the specs, it has a VGA port and using an HDMI to VGA adapter to drop the signal resolution.

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    The hardware in the MacBook Pro is totally capable of driving the HDMI port at lower resolutions, as long as the display supports them. The limitation is strictly in software, specifically in how they've dumbed-down the Displays prefpane from earlier versions. In any case, the answer turns out to be yes, you can use the Mac to drive the 4K display at lower resolutions. See my self-answer.
    – ruief
    Commented Jun 3, 2017 at 19:56

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