Missing 1050x1600 option for dual monitor

I just set up a dual monitor in a vertical (portrait) arrangement. The documentation claims the monitor's maximum (landscape) resolution is 1680x1050. The monitor is not set up as a mirror image.

I have no problem getting OSX to rotate the display 90 degrees. However, when I go into the display settings, 1050x1680 is not listed as an option. The closest resolution available is 1050x1400.

Is there a way to force this resolution through a config file?

It might just be me, but I believe you answered your self in the question.

You said the maximum landscape resolution was 1600 x 1050. But the vertical resolution probably does not reach that resolution because the system thinks the screen has different dimensions (which it does). Once you turn the monitor on its side, the length/width are different. Therefore it changes the maximum resolution to a smaller size.

Okay so it turns out that my iMac isnt detecting the monitor type. I plugged it into a macbook pro and it finds the monitor's type and makes the full 1680x1050 available.
SO NOW the problem is that the monitor isnt being fully detected.

hmm thats odd...