You'll need to supply some more information first. Which version of Suse? What is your video card? Monitor?
From there, you can look at /etc/X11/xorg.conf or /etc/X11/XF86Config (depending on the distro version), to determine what driver it is trying to load. In this file, search for "Driver". It should list the keyboard, then the mouse, and lastly the video driver. For Intel graphics, it will be "i810". For nVidia, it will be "nv", ATi will be either "radeon" or "ati", etc. If it is "vesa" or "fbdev", you are limited to the graphics modes available. Similarly, depending on your monitor, the video card may not support the refresh rates available at the higher resolutions for your monitor (some only support 1280x1024@78hz, for example).
If this is too confusing, send in your spec's and we can go from there.