Enable Automatic super resolution

Go to System > Display > Graphics setting and turn the automatic super resolution default to "on"

In System > Display > Graphics > Custom settings for applications for Skyrim, set Automatic super resolution to "On (keep current display resolution)".

In Settings > Display, change your desktop resolution to the resolution nearest to 800 lines, eg. 1152x768 or 1280x800.

Set in game settings

Launch the game

In the launcher, select Options. Set Aspect Ratio = Native and Resolution to the same resolution chosen above.

Check the Borderless checkbox.

Click OK, then Play.