How to fix refresh rate Issues on Dell monitors after Sonoma update

I had a similar issue, USBC cable only showing 30hz. In my case it was a cable problem, I had to use a specific combination of cable connectors facing up/down when plugging to get the 60hz (no reboots)

From Greatlorens at the top of this feed:

"Can you try resetting the Dell's monitor settings to the factory ones? and then open the monitor setting and check that DDC/DI is OFF, LCD conditioning is set to off, HDR to off, and USB C prioritization to "high-speed setting" These settings demand less power from the monitor. Then check in Mac screen settings in "advance" section if the Show resolutions as list is toggled on. that's the basic I can tell. If Sonoma breaks something else I don't know. I do have a Dell 4k but I have an m2 Mac without these issues you mentioned. maybe it has something to do with m1? but it's a bit strange."

Just wanted to say thank you and that this total fixed the issue I was having. Running a Mac Studio on M1 Max with two DELL 32" monitors. One via HDMI and the other via USB-C. The USB-C was not waking / activating when coming out of sleep mode on the computer. I'd have to turn the monitor off then on again to get the Mac Studio to recognize it. This all happened after updating to Sonoma for the first time. Your suggestions (pasted above on my message) fixed it, so thank you!

Cheers.

I've been running Mojave for 5yrs now, I use a Diamond DS3900PD external Triple display docking station with two LG displays. A third LG display is connected directly to my 2.7 MBP i7 . Yesterday I did a clean install to Sonoma and I am now experiencing display issues.

The display connected directly to my MBP works fine. The 2nd Display connected to the 4k HDMI port on the Diamond DS3900PD also works fine. Now the display connected to the 2k HDMI port on the Diamond DS3900PD stopped working. frustrating to say the least

in my case i'm using an external docking station (Diamond DS3900PD) with two displays, it's connected to my MBP with a USB-C to USB-C cable. So I will try the USB-C cable upgrade, i just ordered a 240W USB4 40Gbps cable.

It has one 4K HDMI and one 2K HDMI, only the 4k HDMI display is working after the upgrade.

I just got a Gigabyte M32UC - a 4k 32" monitor. I hooked it up to the Thunderbolt port on my 2019 27" iMac, and I get a black screen. Fiddle with it, and I find that 60 Hz doesn't work, but 30 does at 4k, or 30, 59.88 and 119.76 work at 2560x1440.

I boot into Monterey and everything works. I boot into Windows 10 and everything works. But Sonoma is broken at 60 Hz.

Yes Sonoma is broken..I've been working with 3 external monitors for the past 5 years, Mojave has been solid. I also use Fusion to run a work Win10 image on a daily basis. This setup has been solid for me...well Sonoma has put a spin on things now.

I tried just about everything on this thread and nothing got my Dell P2719HC monitor to be detected by my macBook Pro immediately after upgrading to Sonoma 14.1.1. My monitor indicated "no USB-C signal detected" and the MBP did not recognize the monitor at all. I did read on another site that switching the USB-C cable end to end was something to try. I thought that was silly and could not figure out what that could possibly do to effect the problem but I did that and it fixed the issue immediately for me.

I wish people would stop posting these non-compliant cable solutions when clearly there is a persistent output issue with 14.0 - 14.1.1

Those of us with Apple branded or known compliant displays like the LG Ultrafine that were sold through the Apple Store have experienced the same wake, detection, resolution, and framerate issues as display users that weren’t sprinkled with magic approval dust.

@iturn2...now that's messed up since both are Apple products. I know its a pain...but have you tried the Apple store? like bringing uour iMac & display for them to figure it out?

Yea..I tried the cable recommendation and that didn't work for me.

I experienced similar, but even more concerning behavior. On attaching HDMI screen (from old VGA->HDMI adapter) the mac showed the new screen but the screen reported no signal. After that the Mac became unstable. PowerPoint slides showed up black and various other glitches. Then tried to use VGA->USB-C adapter, at which point the external screen showed signal, but the instability issues persisted and PPT slide show was all-black or garbled. Rebooted and after that the USB-C connection worked as expected and my corrupted presentations appeared OK again.

I upgraded to sonoma and the external monitor won't work. I've restarted multiple times, unplugged, power cycled the monitor, the docking station. Not sure what else I can try. Checked settings on the Dell monitor. Please fix!

I was good after 14.1.1 on an m1 Air with an LG 24” 4k Ultrafine.

I saw a local listing for the current 5k apple monitor and the person was selling bc they had problems with their m2 Mac Studio on 14.1.2

Time for people to start explicitly listing their configs so the tail chasing or uninformed speculation tamps down.

For what it's worth:

I too had this problem but just got mine resolved. I used a good quality usb c to HDMI adapter plugged in to the port right next to the mag safe adapter, and got a newer better HDMI splitter (5 in 1 out) with a bigger power supply than I previously had, and set my monitor to use HDMI 1.4

I'm not a techie so may be missing something.

I've been running a 2020 MacBook Air with a 4K BENQ monitor and it's worked just fine.

I've just bought a 2023 MacBook Pro 14" m3

On first boot I got an instruction to update the OS - not realising it was going to load Sonoma.

I'm therefore unsure if it's Sonoma creating my issues or the MacBook Pro.

On connecting the new MacBook Pro to the BENQ I get some weird results.

The background wallpaper is the only thing displayed on the BENQ - not the contents/folders etc showing on the laptop screen?

Having the same issues with my two Thunderbolt displays with MBP 13-inch, 2020, Four Thunderbolt 3 ports. Use Apple adapters for the displays and had no issues until upgrading to Sonoma. It's even worst with 14.2 . Complete s@#t show.