On my PC ArcCatalog has a bug where it doesn't display at full resolution (the software itself, not data views). ArcMap sometimes does the same thing. I've attached at image of part of two windows: ArcMap functioning properly (at 1920x1080) with ArcCatalog alongside at whatever subsampled resolution it has adopted.
I am using a Dell laptop with Windows 10, with an AMD Radeon R7 M270 graphics card. I think the drivers are up to date. I think this issue also occurred with Windows 8.1 but it's been a few months since updating.