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User profile for user: Boingo2
Boingo2 Author
User level: Level 1
4 points

13" MBP (2018, 4 Thunderbolt-Ports) issues with Dell U4021QW

I just got the Dell U4021QW and am having issues connecting it to my MBP:

  • When I try to connect it via a DisplayPort-Cable or via Thunderbolt 3 the monitor doenst get a signal from my Macbook.
  • However, the Macbook correctly identifies the monitor in the system settings and acts as it is supposed to when an external display is connected (i.e. it shifts the controllos to said display and charges when connceted to the TB3-cable).
  • I also tried a 13" MBP (2020, M1) which works like a charm as does a work laptop from Lenovo (T14).
  • I am only able to get a picture with my 2018 MBP when I chose a scaled resolution of 1080p or 3840x2160 (for some reason). However, while those work and everything is displayed fluently, the resolution is strongly warped.
  • I usually use a 27" 4K Display by LG with my MBP and have no problems whatsoever (neither over DP nor TB3).


Do you have any suggestions what I can try to get my MBP to work with the Dell Display? Thanks in advance!

MacBook Pro 13″, macOS 11.6

Posted on Oct 8, 2021 4:53 AM

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User profile for user: Boingo2
Boingo2 Author
User level: Level 1
4 points

Posted on Oct 11, 2021 12:23 AM

Thanks for your reply! I already checked the website and unfortunately it didn't solve the issue. I also posted in the Dell community and got a response that seems to explain the issue. I'll paste it here as it may be helpfuls for some:


I'm pretty sure that the Intel GPU built into the CPU used by the

2018-era 13" MacBook Pro only supports DisplayPort 1.2.  The U4021QW

requires DisplayPort 1.4, which supports more bandwidth, to run at its

native resolution and refresh rate.  I realize that the 2018 13" MBP is

capable of running a 5K display (5120x2880), which is even more

resolution than the U4021QW, but that appears to be achieved by

aggregating the two DP 1.2 interfaces available within a TB3 connection

to drive a single display.  The MBP supports this, and some 5K displays

support this as well, but it appears the U4021QW only supports being

driven by a single GPU interface, so 2x DP 1.2 isn't an option.  The M1

MBP supports DisplayPort 1.4, and the T14 might as well depending on

which generation of that model you have.


So, as it seems there is no solution (other than to buy a new Macbook) so I decieded to return the monitor. I guess while USB-C/Thunderbolt is supposed to make linking devices easier it actually complicated some stuff.

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User profile for user: Boingo2
Boingo2 Author
User level: Level 1
4 points

Oct 11, 2021 12:23 AM in response to Lissy_12

Thanks for your reply! I already checked the website and unfortunately it didn't solve the issue. I also posted in the Dell community and got a response that seems to explain the issue. I'll paste it here as it may be helpfuls for some:


I'm pretty sure that the Intel GPU built into the CPU used by the

2018-era 13" MacBook Pro only supports DisplayPort 1.2.  The U4021QW

requires DisplayPort 1.4, which supports more bandwidth, to run at its

native resolution and refresh rate.  I realize that the 2018 13" MBP is

capable of running a 5K display (5120x2880), which is even more

resolution than the U4021QW, but that appears to be achieved by

aggregating the two DP 1.2 interfaces available within a TB3 connection

to drive a single display.  The MBP supports this, and some 5K displays

support this as well, but it appears the U4021QW only supports being

driven by a single GPU interface, so 2x DP 1.2 isn't an option.  The M1

MBP supports DisplayPort 1.4, and the T14 might as well depending on

which generation of that model you have.


So, as it seems there is no solution (other than to buy a new Macbook) so I decieded to return the monitor. I guess while USB-C/Thunderbolt is supposed to make linking devices easier it actually complicated some stuff.

Reply

13" MBP (2018, 4 Thunderbolt-Ports) issues with Dell U4021QW

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