Screen Out of Range DP. GTX 970 Malfunctioning?

[Mephizzle]

Hi,

 

I build the computer below in Juni 2015. Had several problems with serval monitors(at least i though it was a monitor issue)
After getting the latest monitor (LG 34UM95C) everything seems to work like a charm, until today. I turned my pc on and got the following message 'Out of range' (on DisplayPort). When i fiddle with the connection the image as seen in the YT vid appears. I'm guessing the screen itself is fine (as the onscreen menu's look in order) and when I switch to HDMI, I also get the normal image. What does strike me as a little odd is that the distortion stop in the perfect center of the screen. What do you guys think it could be? GPU failure? (should i just RMA it?) or is this a settings problem? 

 

(Also i've tried using an other DP cable, didn't help)

Youtube video: https://www.youtube.com/watch?v=liUQbPzDcbc

Specs:
Scherm LG 34UM95C
Cooler Master Silencio 550 
Samsung 850 EVO series 250GB 
Scythe Mugen 4 PCGH Edition - 120mm
Seasonic M12II Bronze Evo Edition - 750 Watt 
MSI Z97 GAMING 5 - Socket 1150 - ATX 1
Intel Core i5-4670K - 3.4GHz - Socket 1150 
MSI GeForce GTX 970 GAMING 4G - 4GB - PCI-E