Could buy a FreeSync display. Could try D3DOverrider.
I'm using a 100" screen with a 1080p projector via hdmi, not going to buy a Freesync monitor any time soon just to get 1440p50.
I used D3DOverrider in the past, but it became less and less compatible with newer games. Still using RadeonPro when it's compatible or DXtory to cap the framerate when needed. However, as far as I know what D3DOverrider does is to force D3D Triple Buffering (can be done with RadeonPro too), and that doesn't have to do with the problem.
It is very different to cap the framerate at 50 than to have a 50Hz signal with locked vsync and constant 50fps, which is a much more "console smooth" experience.