Setting up a monitor in protrait mode

I want to setup dual displays on my desktop

I have a dell 1704 fpv which i rotated to put in portrait mode however it won't fill the whole screen i have black bars on the top and the bottom.

I can't seem to find other options available in the screen resolution menu.

Any help greatly appreciated.

Also my mouse doesn't sync too great between the two i guess its because one is 17'' and another is 19''

 

You need to tell us how the monitors are connected to the PC, and what type of graphics is used ie, NVIDIA, ATI, AMD or Intel.