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[Solved] [HELP] Sapphire RX Vega 64 + LG 5k2k ultrawide + Displayport 1.4  

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Anchoricex
(@anchoricex)
Trusted Member
Joined: 2 years ago
Posts: 73
April 17, 2019 12:31 pm  

* 2018 13" 2.7ghz QC MBP on latest Mojave (10.4.4 ?)
* Akitio Node
* Sapphire RX Vega 64 8gb
* LG 5k2k Ultrawide (34WK95U-W)

I have the above setup, using the DisplayPort 1.4 cable that was included with the monitor. I'm missing all decent resolutions when using this, the best I can get is 3440x1440 but it's blurry. However when using a TB3 cable from the monitor to the Macbook (no eGPU), I can get the 5k resolutions just fine (but this is pretty taxing on the integrated intel chip).

Things I've tried:
* Reset SMC
* Reset NVRAM
* Tried all versions of DisplayPort on the monitor
* Tried all three displayports on the GPU

I'm inclined to believe this is a MacOS issue, as this guy was able to magically get his working and had one work fine on a duplicate setup. Is it possible I'm not correctly resetting SMC (or maybe NVRAM?)? He says this *may* have solved it for him. I suppose this is somewhat urgent before I'm out of the return window for the monitor.

I attached the only available resolutions I'm able to select from:

Screen Shot 2019 04 16 at 7.08.27 PM

This topic was modified 1 month ago

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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theitsage
(@itsage)
Famed Member Admin
Joined: 2 years ago
Posts: 3938
April 17, 2019 1:25 pm  

macOS is very finicky with monitor refresh rates. DisplayPort connection seems more reliable than HDMI but there's unpredictability too. Using the same set of hardware, I have seen resolution issues in macOS but none in Windows Boot Camp. You should contact Apple Support so that they're aware of this issue.

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mac_editor
(@mac_editor)
Noble Member Moderator
Joined: 2 years ago
Posts: 2048
April 17, 2019 3:58 pm  

@anchoricex the config. shown in the screenshot is a HiDPI resolution running appropriately at 60Hz, right? You can check System Report > Graphics/Displays. Usually option-clicking “Scaled” brings up more resolutions if you haven’t tried that already. Additionally, try SwitchResX to manually configure a resolution of choice and see if it works.

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Anchoricex
(@anchoricex)
Trusted Member
Joined: 2 years ago
Posts: 73
April 18, 2019 12:55 am  

@theitsage

Figured this out, I've seen this issue on this forum a handful of times already so I'm linking this post (my answer to another user who's recently having the same issue). 

My solution here: missing-scaled-resolution-w-vega-64-tb3-lg-34wk95u-w

Truth be told, I have no idea what's going on here but I found someone on the tony hackintosh forum having the same issue with their monitor. Their method added a custom generated .plist file that did the trick. It would seem MacOS definitely has issues generating the correct info for this particular monitor. I don't know if this is LG going out of bounds with how they're sending monitor information to a host or MacOS just being annoyingly buggy and/or lacking in support. At any rate, this did the trick. 

If someone that better understands what's happening here can make a better tutorial/guide/eli5, be my guest. 

This post was modified 1 month ago

Pending: Add my system information and expected eGPU configuration to my signature to give context to my posts


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