I'm using a 4K Monitor, but set the Resolution 1080p.
With Windows 7 I had no problem with recording of my Monitor with OBS (Open Broadcaster Software).
Since my upgrade to Windows 10 the Monitor is shown in the upper left corner. http://puu.sh/jFUbt/428b4aadc0.jpg
When I set the resolution to 4K the monitor will shown correct in the recording, but I don't want to use 4K, because my PC isn't good enough..
I think the problem could be the GPU-Upscaling function of the AMD Catalyst Control Center.
Was the function in Windows 7 there, too?