iMac 21.5" not supporting external monitor native 1920x1200 resolution?

[gong123321]

Have my new 21.5" iMac attached to an external monitor via hdmi. The external monitors resolution is 1920x1200 but the only display options for it in os x are 1080p and 1080i which obviously have a vertical resolution of 1080. According to AMD's site the gpu supports a maximum resolution of 1920x1200 through hdmi. Also, I am not mirroring the displays. This monitor's native resolution was supported on my first generation macbook pro--this is getting very frustrating, does anyone know what the problem could be? Does anyone have a similar setup that works?

 

[Lucianrider]

Have my new 21.5" iMac attached to an external monitor via hdmi. The external monitors resolution is 1920x1200 but the only display options for it in os x are 1080p and 1080i which obviously have a vertical resolution of 1080. According to AMD's site the gpu supports a maximum resolution of 1920x1200 through hdmi. Also, I am not mirroring the displays. This monitor's native resolution was supported on my first generation macbook pro--this is getting very frustrating, does anyone know what the problem could be? Does anyone have a similar setup that works?

Are you sure the monitor supports more than 1080 via the hdmi input?? I had the same issue with a windows 7 machine which was connected via a hdmi to a monitor that also had vga input but the pc only had dvi or hdmi. I could not get it to drive the monitor at anything above 1080 via the hdmi input....

 

[gong123321]

You had a good point so I ordered a thunderbolt>dvi adapter. The settings menu does indeed now give me the option of setting the external monitors resolution to 1920x1200 but there is now a black border of black pixels around the entire screen maybe about a hundred pixels wide on the sides and 80 pixels top and bottom. WTH is going on????