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Macbook pro m1x - external display on usb c stuck at 30hz

I just thew new Macbook Pro m1x. When I connect my external display over USB-C, the Acer XR342CK, the refresh rate is stuck at 30hz. This wasnt the case with my previous macbook pro, from 2018. I cannot see anywhere to change the refresh rate in display settings for the external monitor.

MacBook Pro 15″, macOS 10.12

Posted on Nov 1, 2021 7:01 AM

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8 replies

Nov 1, 2021 7:23 AM in response to stangogh

The Spec sheet I could find do not include a USB-C input, despite saying they ship a USB-C cable in the box.


EXACTLY what cables and adapters are you using to make this connection? mention every cable, hub, dock and device.


Th MacBook Pro M1x is a name invented by the Trade Press to describe what they hoped Apple would release. what is the ACTUAL model-name of the MacBook Pro you have, and what screen size?

Nov 1, 2021 7:42 AM in response to Grant Bennet-Alder

Macbook pro 16-inch 2021, Apple M1 Max; I'm using a usb-c thunderbolt cable.


The monitor does have a usb-c input that can go up to 100hz. When I connect the monitor to my old macbook pro 2018 over usb c, I get 100hz refresh rate. On my new Macbook pro (2021 16 inch) it is restricted to 30 hz. I cannot change the refresh rate for the external monitor connected over thunderbolt on the new MBP.


When I connect the new MBP over HDMI to that monitor, I can choose the refresh rate and it is defaulted to 100hz. When I connect both usb c and hdmi to the same monitor to the new MBP, in the default configuration, I can have both the usb c and hdmi act as extended displays. In this case, I can choose the refresh rate of the hdmi port and it is defaulted to 100hz, but I cannot choose the refresh rate of the usb-c display. However, if I configure the USB-C to mirror the HDMI display, I can choose the refresh rate of the usb-c display connection and set it to 100hz.


I believe this is a bug in the operating system.


Nov 1, 2021 9:57 AM in response to stangogh

<< I believe this is a bug in the operating system. >>


More likely a dispute over DisplayPort 1.2 versus 1.4, or a bug in the response from the display.


to get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

 

This query is only sent at certain times:

• at startup

• at wake from sleep — so momentarily sleeping and waking your Mac may work

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• on invoking Option-(Detect Display) button in Displays preferences (from another display)

 

>> So it is the DISPLAY that tells the Mac what its capabilities are.


--------

In the case of DisplayPort 1.4, this includes data compression, and we have seen a few reports here of displays that report lower capabilities when set to DisplayPort 1.4 (likely because they don't have the compute-power in the display to handle the de-compression at full display speeds.).


The recommendation is to experiment with On-Screen-Display settings, and see if DisplayPort 1.2 gives better refresh rates, since the display does not have to do any decompression on the fly.

Nov 13, 2021 10:48 PM in response to stangogh

I have the same issue. I just received my new MacBook Pro M1X 64GB fully loaded and I'm getting monitor and mouse lag when connected to an external monitor. I've tried several different cable configurations, but the problem remains. I can't figure out how to get the refresh rate out of 30hz. The end result is the entire experience comes with a short delay and almost feels jittery. I move the mouse (apple track pad and/ or Logitech MX anywhere 3) and the cursor is always slightly delayed and imprecise.

Any insight or advice would be appreciated.

Nov 14, 2021 6:06 AM in response to Michael Pierre

Michael Pierre--


This discussion is already too crowded with stangogh complex system details. Adding your system makes it too complicated to keep track of whose is which.


Please start a NEW discussion, give it a title to attract the readers you want, and include the details of what Mac you have, what MacOS you are running, what display you are connecting, and what cable/sadpters you are using to make the connection.


Then Readers can give your issue the personal consideration it deserves.

Nov 14, 2021 6:58 AM in response to Grant Bennet-Alder

Grant - I disagree. He’s dealing with the same issue I am. So it belongs in the same thread. The only reason it is crowded with my system details is because you asked for them. My friends who got a new MacBook Pro as well had the same issue when connecting thunderbolt to his monitor, and he also did not have the issue with his previous MacBook pro

Nov 14, 2021 7:27 AM in response to stangogh

As a senior contributor who has accumulated over 100,000 points, mainly awarded by Users who were helped by these discussions, I can tell you without hesitation that keeping more than one complex setup straight while providing advice is very difficult.


It is with my OWN needs as a Reader in mind that I provided that advice.


If all someone want to say is "I have this problem, too" there is a button for that on your initial post.

Macbook pro m1x - external display on usb c stuck at 30hz

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