I've documented this at
https://wiki.ubuntu.com/X/Troubleshooting/Resolution#Problem:%20%20The%20LCD%27s%20maximum%20resolution%20is%20detected%20automatically,%20but%20lower%20resolutions%20are%20not%20available
I've documented this at
https:/ /wiki.ubuntu. com/X/Troublesh ooting/ Resolution# Problem: %20%20The% 20LCD%27s% 20maximum% 20resolution% 20is%20detected %20automaticall y,%20but% 20lower% 20resolutions% 20are%20not% 20available