The nice thing in SuSE is the ability to run YasT2 even in the command line mode. So all you have to do is
1. Wait for your login screen to show up
2. If you see a graphical login press ctrl+alt+F1 to get a text login screen
3. Login as root
4. At prompt type yast and press enter
5. Now you will get YaST2 control panel like you do in the normal GUI mode, except that here your mouse will not work, you will have to navigate using the following keys, Tab to toggle between the left and right panels, arrow keys to move up and down in those panels, enter key to start/open any service, and spacebar to tick/untick
6. Go to Hardware-> Graphics card and monitor
7. SaX2 will open, and in that you can autoprobe your monitor and configure it. First see if it detects your monitor correctly, many a time the detection is simply wrong. Don't fiddle with the frequencies, try changing the aspect ratios and colour depths. And lastly, test the configuration before you save.
All the best