Are you saying it runs OK with the "nv" driver?
EnvyNG should work, but maybe it will help to give you a detailed procedure. I recommend doing it like this:
First get out of the X server with Ctrl-Alt-F1, then log in at the CLI and shut down the X server with
then do these:
sudo /etc/init.d/gdm stop
1. Back up your existing xorg.conf file
sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf.bak
2. Install and run EnvyNG
sudo apt-get update && sudo apt-get install envyng-core
Choose #1 "Install Nvidia driver", and follow guidance to choose a driver.
3. When you are returned to the CLI prompt, run the Nvidia xorg configuration utility:
4. When it is done writing a new xorg.conf file, restart the X server with
Then, if you don't like the resolution, do Alt-F2 "gksudo nvidia-settings" and set the resolution as you want it for default. It's best to leave the refresh rate set on "Auto". When you have it the way you want it, click the "Save to X Configuration File" button, and save it. Now it's your default setting.