I just purchased a VisionTek Radeon HD7750. Connected two ASUS248H monitors. Monitor one is correctly recognized and the resolution is set at the optimum 1920x1080. Monitor 2 is only recognized with a capability for 640x480.
I have switched the two cables, each monitor can be recognized to support 1920x1080.
The box for monitor ALWAYS has the resolution choice greyed out.
I have installed the latest version of the drivers, and also rolled back to version 16.11.5 as suggested in another post. Both have the same problem.