Level 1

13 points

MacBook Pro 14" 2021 - unable to get 75Hz on Asus MX38VC

Hi fellows,

I am unable to use any 75Hz resolution on Asus MX38VC together with my new MacBook Pro 14" 2021. I had no issues with the same monitor and cable (comes with the display 3.1 USB-c) with MacBook Pro 16" 2017. I have also tried a different cable but the issue persists and I am only able to make it work at 30Hz.

The moment I choose 75Hz the display keeps on trying reconnecting, losing signal and the loop goes on. It stabilises when switched back to 30Hz.

I was thinking of getting a Thunderbolt 3 cable, but since the display only handles usb-c and the other usb-c cable had no effect I doubt this would help.

Monitor set to USB 2.0 which gives max 3840x1600-75Hz

Any ideas what to try?

From Asus manual

Posted on Jan 9, 2022 10:21 PM

Top-ranking reply

Grant Bennet-Alder

Level 10

140,411 points

Posted on Jan 10, 2022 6:21 PM

You may have found that the cable "shipped in the box" is a "lowest bidder" cable rather than a highest quality cable.

You are getting close to the limits of what is possible over a regular USB cable. I suggest you use a high-quality USB-C cable intended for Video and not longer than 1 meter in length.

(and don't mistake the Apple Charge-only cable for a data cable -- it most certainly is NOT.)

Monoprice Essentials USB Type-C to Type-C 3.1 Gen 2 Cable - 10Gbps, 5A, 30AWG, Black, 1m (3.3 ft) - Product # 24285 - $18.49

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50 replies

krisss85 Author

Level 1

13 points

Feb 13, 2022 8:44 AM in response to krisss85

Apple Support got back to me, but not much help right now. It is seen as some compatibility issue between this display and MacBook M1. There is no date or even declaration whether this problem will be fixed in future releases.

Still waiting for any response from Asus then. Simple things can really harm the whole experience with the overall quite decent laptop.

Gior

Level 1

0 points

Feb 22, 2022 3:12 PM in response to Gior

Ok, Apple called back. The Senior technical support said that the engineers had not replied back. Am not confident it'll get anywhere. For what it's worth, my guess is they somehow broke support for the Vesa Modes User Available Timings which support 3840x1600@75hz as per the table that krisss85 posted from the Asus manual. That Vesa Mode must have been fully supported in Big Sur and somehow got broken in Monterey. 3840x1600@30hz is max supported resolution from the PC Timings List of HDMI2.0/DP1.2 input which is what I guess we are running at now. Anyway, Apple support said they would call back again and said they were aware of this thread. Fingers crossed.

krisss85 Author

Level 1

13 points

Mar 30, 2022 11:07 AM in response to synthboffin

I made it working once over HDMI with 75Hz. What I had to do was to shutdown MacBook and start it with HDMI plugged in. However it worked like this only for few hours and then stopped. So yes only 30Hz for now.

Jan 14, 2022 3:08 AM in response to krisss85

I've got exactly the same issue - I have a MacBook Pro 14" 2021 (M1 Max) and Asus MX38VC monitor. I also can't get the monitor to work at anything above 30Hz, either using a high quality USB-C to DP cable or via HDMI. I'm currently using the monitor connected via an OWC Thunderbolt Dock, but it doesn't seem to make any difference if I connect the monitor via that or directly to the Mac. I feel your pain, it's very frustrating! I'm hopeful that maybe an update at some point will fix it...

krisss85 Author

Level 1

13 points

Jan 14, 2022 3:40 AM in response to synthboffin

It might sound awkward, but feel better I am not alone.

I have captured all the logs and video with an Apple support. What is interesting via remote session an engineer was able to see the other screen (once at 75Hz), whereas it was no signal on my side.

I have opened the case with Asus as well, but no response so far still. A pity the 75Hz over HDMI only last for a day and now my eyes are bleeding again.

I will let you know when I hear more from the Apple engineers. Someone should get back to me next Wednesday. Just a warning for people looking to buy a new M1 Macs, it can be problematic.

krisss85 Author

Level 1

13 points

Jan 27, 2022 2:07 AM in response to krisss85

Updated to Monterey 12.2, but no changes here.

Apple Support went back from the escalation, but they response is MacBook Pro 14" 2021 does not support more that 60Hz.

Asking right now why 60Hz isn't then available as an option.

The only think I can recommend you is also call Apple Support and make more buzz around it as apparently they want to ignore the problem suggesting us to use 30Hz.

Gior

Level 1

0 points

Mar 15, 2022 6:54 PM in response to aglick_descript

Not sure why Asus support would tell you that as their manual states otherwise. Also, my setup ran under Big Sur with zero issues at 75hz and full 3840x1600 resolution. It’s a Monterey issue for sure. I’m still waiting to hear back from Apple.

Mar 17, 2022 10:27 AM in response to Gior

And the OSD (when selecting between USB 2.0 or 3.1) also claims 75Hz. Nevertheless for some reason the tech stated that the USB input caps out at 60 and DisplayPort is required for 75; Big Sur only gave me 60Hz (and no other option available) and I would be happy to even get that, so I took it at face value and used it as leverage to escalate my own case with Apple. Hopefully one of us hears something soon...

Mar 30, 2022 7:42 AM in response to ByronF

Hey guys... same problem here. Same Monitor.... and ive updated yesterday from BigSur to Monterey. And now i can also only use 30HZ. 75HZ monitor is flickering black.

So its a Monetery problem.

Apple we need your help... i dont want to sell the monitor....

Mar 30, 2022 6:08 PM in response to Gior

You are not talking with Apple support when you post here. You are talking to other Mac users, who can sometimes come up with a work-around or something else to try. Posts here are not even skimmed by Apple support, are not followed up, are not tracked in any way.

If you want to complain that Apple support is not paying attention to your issue, you first have to contact Apple support:

Get Support

Have your Mac serial number ready when you call.

krisss85 Author

Level 1

13 points

May 27, 2022 6:29 AM in response to synthboffin

Final reply from Asus, but as expected.

"ASUS headquarters confirmed that the problem is not on the monitor side and that the problem needs to be solved by manufacturer - Apple. The HQ tried to contact the manufacturer, but did not receive any useful information."

MoodMan1

Level 1

8 points

Jun 23, 2022 9:38 AM in response to krisss85

Asus PA278CV monitor with a 2018 macbook pro recently experiencing the same exact issues but only AFTER upgrading to Catalina (catatonic). In Mojave, I was able to have a full 2560x1440@ 60hrz or 75hrz without any issues, lag, or monitor resets. It worked beautifully. So if it's not the monitor and not the hardware (or cables). 100% of the finger pointing needs to go to Apple's engineering team.

I have a suspicion the errors have to do with how newer OS's support Reina displays. New monitor interface options were introduced in Catalina that dumbed down the users options in terms of preferred resolutions. If you do some searching around, you'll find the reasons for doing this likely have to do with UI interface scaling vs monitor screen resolution. As to what actually changed in the newer OS's — you got me 🤷

krisss85 Author

Level 1

13 points

Jan 11, 2022 10:39 AM in response to Grant Bennet-Alder

Mac recognises the particular resolution and refresh rate combination, but it is unstable (unable to set it?) and keeps on restarting the screen.

I tried to log more details from the console but couldn't find anything specific in the log flow. SwitchResX doesn't change anything here. I wish I could set 60Hz with this res as that would be sufficient for me, but it doesn't work either. See also ioreg output attached.

Checked with HDMI, but that also doesn't go beyond 30Hz

Jorge

krisss85 Author

Level 1

13 points

Jan 12, 2022 8:33 AM in response to Grant Bennet-Alder

It is there. The result is the same. Macbook tries to set it up but is unable to do so and keeps on resetting the screen.

I jumped on the call with Apple support. Moved to the second stage, but no results.

I have just reinstalled the whole MacOS. Nothing has changed.

Looking at the amount of issues people have with M1 Macs and external ultra wide screen it seems I am not alone.

Jan 14, 2022 4:49 AM in response to krisss85

Yes, it's frustrating but I suppose it's inevitable to experience a few teething problems like this while Apple transitions away from Intel processors/chipsets. I've also had some other frustrations in that, with my previous Mac mini (Intel i7), for the day job I could run Parallels and Visual Studio 2019 on it, so I could work on a .NET Core 3.1 solution and compile it locally....but it seems this is not currently possible on a Apple silicon Mac, as Parallels only supports running an ARM version of Windows and there's no .NET Core 3.1 version for ARM. So for now, for work purposes I've had to resort to using a remote Windows VM. Other than that, all my other Mac software (mainly music related stuff) is working pretty well.

Very interested to hear the outcome of this support call as 30Hz refresh rate is only just usable and I'm really hoping it won't mean I'll have to change to another monitor as I do quite like this MX38VC.

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MacBook Pro 14" 2021 - unable to get 75Hz on Asus MX38VC