I just upgraded to Big Sur 11.1 and noticed that my monitor seemed very laggy. Turns out that my external 4K monitor is running at 30hz on Thunderbolt 3.
What gives? I saw some posts saying that they were having problems on Beta software.
Sorry for the late reply. It's fixed by going to the monitor's setting for now.
System > Advanced > DisplayPort > and Change from 1.4 to 1.2
Sometimes, you have to unplug and plug the TB3 or change to other ports again.
I also have and test with the MBP 13" M1. it works. Hope this helps.
As far as I know there are no plans to fix this bug in the next release, but the bug itself was reportedly confirmed by Apple.
I spoke with 2 techs yesterday and I'm told this is a known issue but there doesn't seem to be any fix for the problem. I spent a little bit talking with a senior tech person that is investigating the issue further.
Hi, I have the same monitor Ben PDQ2720U which works perfectly via TB3/USB-C with other computers but hooking it to my new MacMini M1 it won't refresh at 60Hz for resolutions above 720p, only 30Hz. Did you find any solution eventually of did you hear if Apple acknowledges this finally?
No matter which cable or adapter I use for TB3 ports - DP or HDMI - won't get to 60Hz while via direct HDMI port of MacMini it works - but this is not helping since HDMI is needed for the other monitor, w/o USB-C; and yes, I've tried custom resolutions, EasyRes etc, to no avail;
Well, thanks but my previous message was related to TB3 connection to a 4k display. HDMI works as expected (I do get 60Hz) on MacMini M1 so I don't need an adapter since it has it's own HDMI port. In my message I was mentioning a TB3 to DP cable that still doesn't achieve 60Hz. It looks like no USB-C connection (adapted or not) is outputting 60Hz.
The problem remains - cannot achieve 4k/60Hz via USB-C/TB3. I hope it is a temporary BigSur limitation, not an M1 one.
I have the similar 30hz problem with my MBP 16" connected with BenQ PD2720U via a Thunderbolt 3.
Moreover, the Thunderbolt 3 stops charging my MBP after updating to 11.1.
Big Sur 11.1 - 30hz External Monitor on 2019 MacBook Pro
