Blank screen on Dell 5K

[alphaod]

I've looked online for fixes including things like disabled sleep on the display, disable monitor sleep in OS X and that seems to have fixed my issue until I upgraded to 10.11.3 and now my display just doesn't work in OS X anymore.

In fact I can't get it to work with my Mac Pro or my 15" MacBook Pro, whereas it was mostly no problem before (after doing the all the stuff above). Now, when I boot up the computer, and it will just be blank, so I can't see the login screen or anything. But if I boot into Windows [10], it will work perfectly.

Any ideas?

 

[MacVidCards]

Either post some details or you can't really expect answers.

GPU, how connected, which mode Dell is in, what you did that broke it..., etc.

 

[alphaod]

Mac Pro 2013 model
D500 GPU
Dell monitor is in 5K mode.
Connected via dual mini-DisplayPort cables. I have tried all the possible combination of Thunderbolt ports and none of them work.

Broke when I upgraded to 10.11.3

I can see video if I connect a regular monitor. 5K display works in Windows 10, no issues.

 

[Mikael S]

Mac Pro 2013 model
D500 GPU
Dell monitor is in 5K mode.
Connected via dual mini-DisplayPort cables. I have tried all the possible combination of Thunderbolt ports and none of them work.

Broke when I upgraded to 10.11.3

I can see video if I connect a regular monitor. 5K display works in Windows 10, no issues.

I also have that screen and a nMP.

Usually I find that disconnecting the power cable from the monitor and waiting a few seconds helps.