IIFC, you should be able to get all your available video resolutions to be shown when you type:
dmesg |more
after you log in. It will give you a whole lot of info that you will have to sift through. Perhaps you can try:
dmesg |grep video
or
dmesg |grep mode
In the kde environment, there is a display resolution icon in the system try. Do your resolutions show up there?



