I've been trying to install Ubuntu 12.04 LTS on my desktop most of the day.
The desktop uses a NVIDIA GEFORCE 9800 (GT I think) graphics card.
I am unable to set the correct resolution (1680 x 1050) for the display.
The first problem I had was that of the "Black Screen" during install.
I overcame this by utilising the "nomodeset" switch on the install options (once I'd found how to do that).
The second problem of course was the "Black screen" following the first reboot.
Once again this was overcome by using "nomodeset", this time by "editing" the GRUB.
This gave me a resolution of 1280×768 which, the Displays GUI allowed me to change to 1280×720 (appears to fit on screen).
I then tried to install the NVIDIA drivers.
1) using additional drivers
2) manually by downloading driver and installing in root
As soon as NVIDIA drivers are installed – resolution become restricted to 640×480 (max).
At this resolution Ubuntu GUI is not usable as most screens are larger than the display. Removing the NVIDIA driver and removing the XORG.CONF file does not lift this restriction.
I have tried most things that I have found and that were vaguely intelligible, but nothing appears to get me closer to a resolution of 1680×1050.
UPDATE: reinstalled Ubuntu 12-04 and used the "NoModeSet" in the Grub to restore the resolution to 1280×720, which is at least usable. Will live with this for now.
Best Answer
I have been having resolution problems with my brand new Ubuntu 12.04 LTS installation and I couldn' t even see the choice of the 1680x1050 resolution. But then it was so easily and user-friendly solved: Just went to Additional Drivers in the System Settings tab and activated the NVIDIA accelerated graphics driver(post-release updates)(version current-updates) and it worked for me. Good luck!