It is equivalent to a smaller size screen with the normal horizontal resolution (vertical columns). 800, 1024, etc. It is easy to see that the horizontal stretching option is enabled in the BIOS, the Windows boot screen looks distorted too. Yet another visible side-effect is that a video adapter pixel no longer corresponds with an LCD panel pixel, causing the display to get blurry. That tends to be less noticable in DirectX games as compared to windows with text using a font with a small point size.