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Black screen when using DisplayPort with a 4K display

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Joined
Dec 1, 2016
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Motherboard
Gigabyte Z77-DS3H
CPU
i5-3570K
Graphics
RX 570
Mobile Phone
  1. iOS
I bought a 4K display. My old GTX660 supports 4k@60hz with DisplayPort (testes with Windows 10 when it works well) and only 4k@30hz with HDMI so of course I want to use DisplayPort.

The problem is that when I have the display connected using DisplaPort, Clover shows, the Apple logo shows and then in maybe half of the loading process the screen turns black saying "no signal". The macOS boots, I see the login screen when I connect my second DVI display.

Also when I connect the 4K display using HDMI the macOS boots fine, but just 30Hz. I have the latest NVIDIA web drivers (378.05.05.05f02) installed and enabled them at boot using the new method.
 
OS X sometimes doesn't like DP 1.2 displays, so I'd suggest to switch your display to DP1.1 mode (if possible), and switch back to DP 1.2 afterwards.

I'd also try to use your 2nd screen to access the display settings of your 4K monitor. Make sure the appropriate resolution/refresh rate is set and also push the "Detect Displays" button.
 
I booted into Windows and disabled DP 1.2 in display settings. I then rebooted to macOS and the result was the same, "no signal" no the 4k display. When I log in using the second display and press "Detect displays" in SwitchResX nothing happens.

Btw I think disbaling DP 1.2 is not a solution, becase only DP 1.2 does 60Hz on my GPU. When I disabled it in Windows I noticed the cursors started to lag like in macOS, meaning 30 Hz.
 
The DP1.1/1.2 settings are going to be in the monitor's settings. You should not have to boot into Windows to change it.
 
I changed in in the monitor menu as I said. The fact that it did it booted in Windows should note matter.
 
Curious ... when I connect the hdmi and dp at the same time, after logging with the hdmi if I change to DP on the monitor I can see osx as 2 screen ¿? ¿? The problem seems to be that Sierra understands HDMI as a primary connection ... that's why the screen was black .. I understand that Sierra does not activate the second display until login .. is there any way to say that the DP connection is the main one? Test to change a DP After login...The difference is that in my case I get @ 60 Mhz with the two connections but I would like to leave the DP as main not vice versa. Im used a GTX1080 but the problem are similar.
 
I was having the same issue on my Dell U2715H.

Disabling DP 1.2 help resolve the black screen issue.

I used the monitor's OSD(On screen display) menu. Menu > Display > DP 1.2 > Disable.
 
I was having the same issue on my Dell U2715H.

Disabling DP 1.2 help resolve the black screen issue.

I used the monitor's OSD(On screen display) menu. Menu > Display > DP 1.2 > Disable.

I bought a new GPU in thea meantine so I no longer have this problem but I want to say that disabling DisplayPort 1.2 is not a good solution. You need DP 1.2 to be able to drive the 4K display at 60Hz. Without DP 1.2 you only get 30Hz which is laggy and unusable.
 
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