I suggest you to check the troubleshooting available on this site:
Keep in mind that the graphics controller drivers will support just about any video modes (within reason) that the Monitor’s EDID (Extended Display Identification Data) claims to support, as well as modes defined within the Video BIOS Table (VBT), plus a basic set of static modes (mostly for monitors with no EDID): 640x480, 800x600, 1024x768, 1280x1024, and 1600x1200. Each Original Equipment Manufacturer (OEM) may limit resolutions within the VBIOS, which is an active part of the BIOS. Manufacturers according to their system designs and target markets can do these changes.
So, some video resolutions may be avaialble only if you install the dicver of the monitor connected and if the custoized driver provided by your motherboard .manufacturer is installed