Can't get my 2019 MacBook Pro to recognize my new Dell U4021QW

Hi,

The problem is with the Dell cable. I had my own CalDigit TB4 cable working fine when I received the monitor but then decided (big mistake) to switch to the Dell cable provided with the monitor to test that out. This is when the problems started and the monitor will not detect my mac mini (had to connect / disconnect cable, switch inputs, etc to get it going). Gone back to my own TB4 cable and problem disappeared...

There have been reports of displays that will not work at high resolution AND DisplayPort 1.4 (which requires the display to un-compress display data on the fly) If the display's computation is not quite fast enough, it may refuse to run at highest resolution.

However, if you back the display's internal settings back to DisplayPort 1.2 (no no compression required) some of those same displays work just fine.

Since the Mac bases its resolutions and settings on what the DISPLAY reports as its capabilities, the Mac sees the changes and adjust its resolutions and protocols.

The front port is not a input port, so yes, using one of the back ports would be the way.

Looking in the manual, it Sounds like the incorrect input is selected for it.

Try selecting a different Input source from the Monitor's onscreen menu:

http://ftp.dell.com/manuals/all-products/esuprt_electronics_accessories/esuprt_electronics_accessories_monitors/dell-u4021qw-monitor_User%27s-Guide_en-us.pdf

You may have the wrong input source selected there.

To display over 4096 pixels wide, your MacBook Pro must be running Big Sur and be a model from 2017 or later. Older models can support resolutions over 4096 wide, but require TWO cables to connect to the display.

There are a few displays that are hesitant to use DisplayPort 1.4 settings in the display. The difference in DisplayPort 1.4 is that it allows comprised data, and a few displays can not quite decompress fast enough, so they limit resolution or refresh rates when using DisplayPort 1.4 settings in the display.

The Mac queries the display, and will match what the display tells it for capabilities. So if you need to step the display on-screen-display settings down from DisplayPort 1.4 (compressed) to DisplayPort 1.2, the Mac will quickly adapt.

Apple is limiting the output of the GPU to 30 Hz for anything that is over 3840X1620, even know they have 5120-by-2880 resolution at 60Hz list on the specs. If you look up the spec of the Intel has it listed at

4096 x 2304@60Hz. One of the works around I found was to use Disable Monitor https://github.com/Eun/DisableMonitor to output at 5120X2160@30 Hz.

I was able to land a killer deal on an MBP 16, and it has the ability to output at 60Hz using Disable Monitor.

I've also contacted Apple about this issue, and they are aware but are not going to make any changes..

I have Macbook Pro 13'' 2019 and have the same issue with U4021QW. I cannot get any resolution @60 hertz. But can get resolutions max 4608x1944 @30 hertz

Contacted with Dell and Apple Support, here are the results:

Dell Support:

They said; "We have escalated the case to our higher team and this is not an issue with the monitor. This is a limitation on the Mac.

U4021QW Native Resolution 5120 x 2160 (DisplayPort: 60 Hz, HDMI: 30 Hz) is not compatible with NVIDIA or AMD at this time, the 2019 Mac may have the cards from this version. "

When I respond to them that I have Intel Processor. Their reply is "No Issue on the Monitor, the problem is caused by Macbook Pro" without any extra diagnoses.

Apple Support:

The Macbook Pro supports "One display with 5120-by-2880 resolution at 60Hz at over a billion colors" https://support.apple.com/kb/SP799?locale=en_GB

Tried multiple troubleshoot steps with the Apple support (Cleaning Cache, etc.) but nothing was able to solve the issue.

The support team suggested reinstalling the OS but I do really believe that It will not solve the issue because it obviously looks like a hardware issue.

When I check the Intell docs regarding processor tech spec, I have recognised that the processor just only support max

4096 x 2304@60Hz

https://ark.intel.com/content/www/us/en/ark/products/192996/intel-core-i7-8557u-processor-8m-cache-up-to-4-50-ghz.html

Now, Apple support has been escalated the case to Engineering Team with the spec of the processor. I also found some discussions about other Macbook models and Ultrawide monitor have been suffering from the same issue.

It looks like, we should be very careful with MacOs and Ultrawide monitors.

I am on the second Dell TB4 cable (they shipped another on ejust in case) and all have same issue. Unless, you unplug/replug the cable the monitor fails to wake up. I have FileVault enabled so boot takes longer. If you don't have FileVault enabled maybe you don't have the same issue. This is not a good reason for Dell though not to have tested this with FileVault and checked the cables they shipped. A cheap chinese cable I got works and the same for CalDigit's TB4 cable. Apple TB also fails miserably like Dell's and it is the most expensive of them all.

The default USB-C cable that comes in the box with your Mac is a Charge [ONLY] cable. It has only enough data conductors to run a keyboard or mouse, or negotiate between charger and computer at extremely low speeds.

It will show the display as connected, and supply no picture whatsoever.

Yes, to is the left back port you need to connect too. Try the right back port. Plug the charger in... it should work.

I have a 27” LG monitor (the one Apple sells) hooked to a 2017 15” MacBook Pro. From time to time the monitor won’t fire up. I hook up the monitor to my iMac and it fires up. Hooking it back up the MacBook it works again. If you have another Mac/computer try doing that. If it doesn’t fire up on the Mac/computer something wrong with monitor.

@30Hz no problem, needed to use DisableMonitor to get it working.

I'm just waiting for Apple support to call me about this issue, how to get 60Hz going since it's in the specifications.

Also have a Dell support case open on the topic, so I think we'll get an answer soon.

Hi, I had the same (exactly) issue with my MacBook Pro 13" 2020 M1 back end of Jan beginning Feb. I got a new/exchange one from DELL and now it works quite well since more than 3 month. I use 2560x1080 with 60Hz on the Thunderbolt connection. For me a fantastic solution! Every day at least 8 hours. Sometimes it takes 4-5 seconds that my MB recognize the monitor but no further issues.

On a Mac M1 Mini / Big Sur :

• 5K2K resolution only over TB cable. Dell cable fails to wake up the monitor same issue with Apple 0.8m TB cable and message "No Thunderbolt (90W) signal from your device." comes up. If you unplug the Dell TB cable and replug it things get resolved. I have since used a CalDigit and also a Chinese TB cable and both are able to connect on boot with not issue.
• 4K resolution using HDMI port but I need to run in PIP/PBP mode to match the screen ratio. Mac M1 does not support 5K2K resolution over HDMI but this seems to be an Mac M1 issue since my PC works fine using same HDMI cable.

On a Mac M1 Mini / Big Sur :

• 5K2K resolution only over TB cable. Dell cable fails to wake up the monitor same issue with Apple 0.8m TB cable and message "No Thunderbolt (90W) signal from your device." comes up. If you unplug the Dell TB cable and replug it things get resolved. I have since used a CalDigit and also a Chinese TB cable and both are able to connect on boot with not issue.
• 4K resolution using HDMI port but I need to run in PIP/PBP mode to match the screen ratio. Mac M1 does not support 5K2K resolution over HDMI but this seems to be an Mac M1 issue since my PC works fine using same HDMI cable.

Just adding my experience to this thread. I am considering returning my U4021QW, and this is my last resort.

The monitor works fine with my windows laptop at full resolution with the supplied USB-C/Thunderbolt but not with my 2018 MBP on Big Sur 11.3 (updated this morning).

When I select resolution "default for display" the monitor does not recognise the signal coming from the Mac. When I option-click "scaled" and select 5120 x 2160" the same thing happens (no signal recognised). If I unplug the Thunderbolt cable at this point the Mac will reboot (ie. crash) without warning.

I am able to select resolutions lower than 5k and get a picture, and also interestingly in PBP mode I can reliably run the monitor at 4096 x 2160 (so I can use 80% of the monitor reliably :-).

So the issue seems to be limited to driving the 5k resolution.

Any thoughts from an Apple rep or anyone else? It seems effort has gone in to ensuring the M1 works with this monitor, and I hope that the intel MacBook Pros can get some love too.