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Display locked at 30hz after sleep

I

iandk

macrumors regular
Original poster
Aug 10, 2019
162
65
Hi,

I recently updated to Catalina and got a Elgato Thunderbolt 3 Dock a few days ago.

But unfortunately I had to notice, that my external 4k monitor gets reseted to 30hz and the default scaling mode.

Unplugging the USB C cable/ turning the monitor off seems to work.


Does anyone have the same problem or an idea how to solve this issue?


Macbook: 13" 2017
Thanks!
 
Yup, same issue on my 2018 13” MBP with a Dell 4K monitor. I’ve tried everything, multiple cables, docks, reformats, reverting to Mojave, SwitchResX, NVRAM reset, nothing fixes it. I didn’t have this problem with Mojave with the same hardware setup. Absolutely maddening.
 
Same thing was happening to me with with running two LG 4K monitors through a Caldigit TS3 dock. Upgrades to the TS3 Plus dock and now everything works fine so far. Kind of bs though since the TS3 is suppose to be compatible with 2 4K monitors....Caldigit support was useless as well.
 
Oh boy, I hope it's not caused by my Dock.
It's a Elgato Thunderbolt 3 dock
 
I’ve experienced this issue with both with my Caldigit TS3+ and with the monitors plugged directly into the Mac via TB3 to Display Port. Oddly, connecting via TB3 to HDMI doesn’t cause the issue. I’m using that for now, but prefer using Display Port.
 
Just got my new 16“ and it has the same problem.
Monitor is connected via Displayport of the Elgato Dock
 
yea, definitely sucks.
Did anyone find a workaround?
 
Just connected my LG monitor via it's USB C cable to the second port of the Thunderbolt dock.
Seems to work fine until now, but I'd rather like to use Displayport to have that USB C port still available.

Hoping for a fix or workaround soon.
 
This must be a GPU driver issue. My (new 16", have had 2 and both resulted with this issue) Macbook has this issue since I got it around a month ago. However if I use my partner's Macbook (I think 2016 13" model with no dGPU), there are no issues whatsoever.

Infuriating. Hopefully Apple say something about this soon.

Edit: Is there any way to 'deactivate' the AMD GPU or select the Intel GPU to be used when my monitor is connected?
 
Intel GPU has the same issue. It’s definitely a software issue. I had the same hardware setup with Mojave, never had an issue. Once I upgraded to Catalina, the problem started.

Even after reverting to Mojave, the issue persisted. To me it seems like a firmware issue.
 
Really hoping for a fix. For now I will just use indefinite sessions with Amphetamine to avoid the MBP sleeping...
 
I get the same on a Caldigit TS3 plus. I'm positive it's Mac OS that's the issue though because the problem exists when using a MBP 2016 and a MM 2018 in Mac OS. They both have bootcamp and neither have the issue when using that.
 
Try toggling the resolution to the highest scaled mode and then back to default.

This happened to me (using 2x4K monitors on a Caldigit TS3). One day, one of the monitors went to 30hz and no amount of unplugging/replugging monitors and dock would change it.

Toggling the resolution to scaled and then back to default fixed it.
 
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lastobelus said:
Try toggling the resolution to the highest scaled mode and then back to default.

This happened to me (using 2x4K monitors on a Caldigit TS3). One day, one of the monitors went to 30hz and no amount of unplugging/replugging monitors and dock would change it.

Toggling the resolution to scaled and then back to default fixed it.
Click to expand...
THANK YOU! This fixed it for my TS3+
 
Toggling the highest/lowest resolution did not consistently change my refresh rate.

HERE'S A CONSISTENTLY WORKING SOLUTION:

1. Open display settings for affected monitor.
2. Opt + Click "Scaled" option to open additional sizes.
3. Choose "show low resolution modes" check box and change the Refresh Rate.
4. You may initially find that the refresh rate is gray and not editable. (unlike my screenshot here). In that case, change the rotation field to anything else (90, 180, 270), then switch back to standard/normal rotation. The refresh rate field will be editable.
1624654399624.png

This works 1000% of the time.
 
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