Big Sur 11.1 beta forces external 4K display refresh rate to 30hz

I got it working, finally! Here's the step I did (BenQ PD2700U):

1. Plug in your external monitor via DisplayPort to USB Type-C
2. Go to System Preferences -> Displays
3. On both Internal and External Display, select Resolution: Default for display
4. it should automatically detect to 60hz

Thanks to this reference: https://apple.stackexchange.com/questions/336725/external-display-works-on-30hz

This works perfectly for me. Hope it helps.

SOLVED after much pain and suffering. Steps I took:

1. Changed dongles. Was previously using a USB3 > HDMI dongle, switched to this: https://www.apple.com/shop/product/MUF82AM/A/usb-c-digital-av-multiport-adapter
2. I was using the display in slightly less than default resolution (stuff was so small!) ... but in order to get it to flip to 60Hz I had to set the resolution in Display Preferences to "default for this display", let it update, and then it flipped to 60Hz.
3. Then I was able to flip it back to the lower resolution and it maintained the higher refresh rate.

Word to the wise for other users and Apple – the first support person I spoke with simply told me this is a known issue with no fix, and was ready to send me on my way. Only when I escalated to a senior support rep did we come up with the idea of trying a different dongle, etc. Apple could you please have someone for $10 an hour go through and put the solutions in these threads when they exist? Apple I still love you, but 🙄

oriondesign wrote: "Apple could you please (...) put the solutions in these threads..."

Apple isn't here. Go here:

Apple Website Feedback

Also, it's anticipated that the original poster will mark the appropriate reply as "Solved".

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I have a BENQ PD3220U using DisplayPort connection to usb c on MBP16 on 11.2 Big Sur

1. I changed DPort settings to 1.2 form 1.4
2. Got into advanced mode on Display setting by holding ALT and clicking scaled https://youtu.be/-epAJtrPmLE?t=113
3. Click manual low resolution
4. then click 60Hz

Worked for me, hopefully for you too.

I encountered this issue as well after upgrading to 11.1 (Released version). I assumed it was because of doing the upgrade while it is connected to my external monitor. Is that a possibility? I am using a BenQ PD2700U monitor and after upgrading to the said version, even when using a display port to USB-Type C, which is working at 60hz before, is now capped at 4K@30hz.

Had a similar problem with my 2017 iMac 4K running macOS 11.1 and an AOC U2790VQ external monitor. Originally connected via Thunderbolt 3 to HDMI cable and refresh rate would not exceed 30 Hz. Using a UNI USB-C to DisplayPort cable rated at DisplayPort 1.2 fixed the problem and it is now 4K@60 Hz or 2K@165 Hz. Apparently there is an issue between Big Sur 11.1 and DisplayPort 1.4 on some monitors.

The beta can not be discussed in the public forums.

This video has helped me access the now hidden refresh rate settings in 11.1 but I am still unable to set 60hz at 2K res on my display: https://www.youtube.com/watch?v=2bJTf8TBGC0

Under 'display' in 'About this mac' my BenQ PD2700U is showing as a 61-inch monitor ha! This is so bad.

I tried everything but I'm unable to make it work at 60Hz.

Furthermore, I see my MBP 16 2019 retina monitor is set as a max res at 2048x1280@60Hz instead of the native max res 3072 x 1920.



This worked for me! I previously tried an SMC reset, which did nothing. MacBook Pro 16" 2019.

Doing this makes my screen and font size incredibly small. How do you adjust this without scaling ?

I think this has been totally fixed on the latest update, 11.2.1. Just tried doing the same tweak (setting all Display settings to Default) and it auto adjusted to 60Hz.