The Y50 is a 15.6" screen with 1920x1080 resolution and the External Monitor is a 20" screen with 1600 x 900 resolution, making the resolution disproportionate to the actual monitor size. When I go into screen resolution and try to get the monitors scaled appropriately to each-other any adjustments I make are accompanied by a "input signal out of range" error on the large monitor, a "resolution too low" on the smaller monitor, or skewed graphics. If I give each monitor their recommended resolutions the 20" monitor appears smaller than the 15.6" monitor, making the applications on the external monitor huge and teeny tiny by comparison on the laptop monitor, not to mention the magic teleporting mouse pointer.
When I try to use the scaling options (control panel >> display) it changes the scale of both monitors and does not help when trying to make their virtual position line up with there physical position.
From what I can tell Windows is reading the monitor as a 1600 x 900 sized monitor with the same DPI as the Y50, which it isn't. Is there any way to tell Windows that the external monitor has a lower DPI and is a 20" monitor, not a 13" monitor, while keeping the high resolution on the laptop monitor?