Forcing RGB with 4K Dell monitor limits resolution to 1080p

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Forcing RGB with 4K Dell monitor limits resolution to 1080p

I’ve successfully forced my Dell S2721QS to use RGB instead of YPrPc colour using an EDID override, but now my 4K monitor is limited to 1080p.

Changing the monitor to RGB mode made colours go all pink and green—apparently because the Mac was still outputting YPrPc—so I used a ruby code from GitHub to generate an EDID override .plist file (it’s all a bit of a black box to me), and even tried to generate my own UHD RGB EDID with a free editing software, but the monitor didn’t even turn on, so I clearly missed something despite thoroughly researching timing parameters etc.

Does anyone know a solution or workaround? I’ve heard DisplayPort, but can I just use a USB-C to DP cable or do I need to buy an ugly, cumbersome Apple brand dongle.

MacBook Pro 13″, macOS 11.6

Posted on Apr 15, 2022 4:10 AM

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Urquhart1244

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Apr 15, 2022 5:01 AM in response to make-me-happy

It’s seems like a bandwidth issue. Does it have HDMI 2.0 ports and DisplayPort 1.2? Each version is specific to a maximum allowed bandwidth, and will require cables with matching capability. Verify that you use a 18 Gbps HDMI cable for HMDI 2.0 connectors on both ends. If you use a HDMI adapter on your Mac, then verify that is is at least HDMI 2.0 as well.

Verify the mix of resolution, refresh rate, video dynamic range (SDR/HDR; 8-bit or more), and chroma in your settings. 4K HDR 60Hz RGB exceeds the HDMI 2.0 limits. One of these properties will have to give. Non-RGB color spaces allows for reduced chroma subsampling, to save a bit of bandwidth, and thereby allow other video properties to be higher. If you want it all, then you’ll have to buy a higher end monitor.

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Forcing RGB with 4K Dell monitor limits resolution to 1080p

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