Hi. I have Dell Optiplex 990 (Prosessor Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz) with AMD Radeon 6450 (1GB) graphic card - running Windows 10 Pro with all latest updates. Monitor (Samsung SE790_S34E790C) is connected with a displayport cable (new) to the displayport on the graphics card. When I select resolution of 3440X1440 and 50Hz, everything seems normal, but if I select 60Hz, the screen will show a flickering stripe across the screen. (I have added a small video to show the problem). On every restart I also get a windows message on screen "A display capable of DisplayPort v1.2 data rates and multi-streaming is currently connected to a connector that does not support DisplayPPort v1.2. Therefore, only DisplayPort v1.1a features are supported. For example, only the first display in a chain will be enabled".
I have tried many things, but the "flickering stripe" across the screen, never goes away - unless i lower refreshrate to 50Hz.
Any help on resolving this issue would be great.