Upgraded wife to 10.9.1, since then her 24" 1920x1080 monitor does not display proper res. In Prefs, the Preferred res is 800x600, max scaled res is 1600x1200. It worked fine in SL. The monitor's controls offer no help, not their job anyway. Turning monitor on/off does nothing.
She has a 2010 Mini, the monitor is a year old AOC.