Problem with 2018 MacBook Pro and external displays

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Level 1

11 points

Problem with 2018 MacBook Pro and external displays

I'm having trouble getting my new 2018 15" MacBook Pro to display on my two external Dell U2715H monitors. The system does seem to at least recognize the monitors are connected (they appear in Display preferences) but nothing appears on the screens. I have tried connecting the monitors individually directly to my system as well as through the dock setup outlined below and no combination of cables/monitors gives me a working external display.

My current setup is:

1 Dell U2715H monitor connected via DisplayPort cable to Belkin Thunderbolt 3 Dock
1 Dell U2715H monitor connected via DisplayPort to USB-C cable to Belkin Thunderbolt 3 Dock
Belkin Thunderbolt 3 Dock connected to 2018 15" MacBook Pro via USB-C cable

When I connected my wife's 2017 13" MacBook Pro with this same setup the displays worked exactly as expected and the monitors worked previously with my 2015 15" MacBook Pro as well. I only see a problem when connecting to this machine. I suspect an issue with the new Radeon Pro 560X GPU, but that's only a guess at this point.

As I mentioned above, I have tried:

Connecting each monitor directly to the laptop to remove the dock from the setup
Swapping out the USB-C cable running between the dock and my laptop
Resetting the NVRAM (Reset NVRAM or PRAM on your Mac - Apple Support)
Resetting the System Management Controller (How to reset the System Management Controller (SMC) on your Mac - Apple Support)
Disabling the automatic graphics switching option in the Energy Saver settings
Using the "Detect Displays" option in the Displays setting panel (hold option and click "Gather Windows")

Have others seen similar issues with these new machines? Are there other options anyone would suggest?

MacBook Pro TouchBar and Touch ID, macOS High Sierra (10.13.6)

Posted on Jul 28, 2018 3:16 PM

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Answer 1

Jul 28, 2018 3:46 PM in response to ckboyle

"USB-C should be thought of as an Adjective, and not a Noun."

When you say you are using USB-C cable to make the connection, this says NOTHING about what type of cables you are actually using -- it only specifies the connector at one end.

The best counter-example is the Charging cable: It has only power and USB-2. It has no hope of driving any display, ever.

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Answer 2

Aug 1, 2018 12:55 AM in response to ckboyle

I had same problem with my 15" 2018 rMBP running an external 24" CinemaView monitor until I used a UpTab thunderbolt to usbc connecter and now it works like a champ.

Be advised my external display has a pigtail with 3 leads: external power, usb and thunderbolt. If you have same this SHOULD work for you also.

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Answer 3

Aug 16, 2018 6:52 PM in response to ckboyle

Wait, you are trying to support a second display off a Dock?

What version of MacOS is being used with this? and what version of MacOS with the 2017 MacBook Pro?

This may involve DisplayLink software, and a security "fix" Apple introduced in a recent version --10.13.4, described here:

https://support.displaylink.com/knowledgebase/articles/1849342-important-informa tion-on-macos-10-13-4-update

.

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Answer 4

Aug 16, 2018 6:50 PM in response to KGphilly13

KGphilly13--

You should "Follow" this thread, in case a fix is found:

Re: 2018 MacBook Pro Target Display Mode Not Working

.

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Answer 5

ckboyle Author

Level 1

11 points

Jul 28, 2018 3:55 PM in response to Grant Bennet-Alder

I agree I could have been more specific regarding the cables themselves - the specific cables used are the Cable Matters USB Type-C to DisplayPort cable, the Cable Matters DisplayPort cable, and a Thunderbolt 3 cable connecting the laptop to the dock.

Again, these same cables and this same setup worked on a 2017 MacBook Pro running the same version of OSX so I am inclined to believe the issue lies not with them but with something on the laptop itself.

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Answer 6

Aug 16, 2018 3:57 PM in response to ckboyle

I am having a similar issue with a brand new 2018 MacBook Pro (13") w/touchbar using a mid-2011 iMac as the secondary display. I am utilizing a apple TB 2 to TB 3 adapter (Apple support has confirmed my setup is correct and should work). I have a mid-2015 MBP that I use with the iMac as a secondary monitor and it works perfect but with the new 2018 I get a black screen and just like you I can see an external monitor is recognized in System Preferences. I have been searching for a solution and have come up empty and apple says I am set up right and they don't know what's wrong.

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Answer 7

ckboyle Author

Level 1

11 points

Jul 28, 2018 3:57 PM in response to tethfrog2321

Yes, sorry, I neglected to mention above that I did try Safe Mode as well with no success. That one slipped my mind when I was making the list.

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Answer 8

Jul 28, 2018 3:45 PM in response to ckboyle

Hi,

Try using safe mode and see if that helps

Use safe mode to isolate issues with your Mac - Apple Support

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Problem with 2018 MacBook Pro and external displays

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