I would think you would just see a screen with a mishmash of mis-aligned rows of data flicking all over the place like you get when you try to set a res that isn't available on a given monitor. I did this on an old VT220 terminal recently which was couldn't do a 1024x768 mode, so it just displayed scrambled input. I don't think you can force the monitor hardware to try to do something outside of its design as such, but saying that I do recall even in the Amiga days people warning against trying to make your monitor do things it wasn't designed for.
Speaking of monitors, though, has anyone with a flatscreen LCD display noticed that it takes several frames for an old frame of graphics to `fade` from the screen, ie some of the color value or brightness is retained in the pixels and so when you have normally smooth moving objects like at 60hz, you get this blurred streaking motion-blur type of effect rather than a really crisp graphic? I find it somewhat annoying.
Speaking of monitors, though, has anyone with a flatscreen LCD display noticed that it takes several frames for an old frame of graphics to `fade` from the screen, ie some of the color value or brightness is retained in the pixels and so when you have normally smooth moving objects like at 60hz, you get this blurred streaking motion-blur type of effect rather than a really crisp graphic? I find it somewhat annoying.