[THEBERBSTER]

Changing AMD Radeon GPU Settings
This is a generalisation for AMD GPU’s yours maybe different but the principal needed is just the same.

Go to > AMD Radeon GPU Driver Settings In The AMD Catalyst Control Centre.
Click the Right Mouse Button > Select AMD Catalyst Control Centre.
Go to > Advance View > Settings > Options
Under My Digital Flat Panels
Select > Properties
Change the following settings options as available:
Image Scaling > Enable GPU Scaling
or
Image Scaling > Maintain Aspect Ratio
or
Image Scaling >Scale Image To Full Panel Size
Apply to save the changed settings.
Confirm.
Re-boot your system.