[Help] Bad signal through displayport

[dnlnrdn]

Hello everyone! For my first post on the forums I bring you the hardest of problems.

I'm having an issue connecting my rMBP 2014 to my LG monitor via mini display/displayport cable. The resolution is correct but color and contrast is WAY off. There's no real blacks nor whites anymore. Everything is just a low contrast, gray mess.

Thing is, this configuration worked fine om my rMBP from 2012.

Bought a minidisplay to DVI adapter today and to my surprise, color and contrast was good again, but resolution limited to 1920x1080 (this is a limitation of the adapter, monitor is 2550x1400).

Of course I want the full resolution and the same, good contrast/color as I've always had. It's as if the new computer doesnt have enough power to push the full signal through the displayport cable like it's always done.

One possible explanation is that the different graphics card is affecting the performance of the minidisplay port...I've tried calibrating the monitor, checking settings, factory resetting it, fresh install of Mavericks and Yosemite, buying a new minidisplay cable. NOTHING works.

Any ideas?

 

[DeltaMac]

If you have tried your LG monitor on a different computer, and the displayport connection on the monitor is not working properly now...then use a different connection, such as DVI.

If you want your full resolution on DVI, you'll need a dual-link DVI adapter, like this one: http://www.monoprice.com/Product?c_id=104&cp_id=10428&cs_id=1042802&p_id=6904&seq=1&format=2

 

[dnlnrdn]

I should be able to get the full resolution and color through displayport without having to buy the adapter...

 

[DeltaMac]

Yes, you should, assuming the monitor is still working OK on that displayport input.
And, that is one of the advantages of the mini DisplayPort to DisplayPort connection - it will give you whatever the system is capable of displaying with that simple connection.

Have you tested your displayport input connected from a different computer? Maybe that port has a general failure on your monitor?

You might be able to use mini displayport to HDMI (or HDMI to DisplayPort, if you prefer)

If your only choice to get good color is the monitor's DVI connection, then you will need the dual-link adapter to get full resolution. That's how DVI works...