A new Ubuntu 12.04 version has been released just a few days ago. You grab an ISO image of the OS from Ubuntu.com, burn it to a CD and do a fresh install of Ubuntu 12.04. Everything seems fine, it is working nice and quick on your laptop. But once you unplug it, your Nvidia GPU keeps on working. Well, at least the fan is running on full speed and your battery is getting drained faster than you expected. What do you do? Well, the first thing you may try is to install Bumblebee:

Installing Bumblebee

Bumblebee is an opensource program that manages switching for your Optimus graphics card. Official guide

Run these commands on your Terminal:

• Add Bumblebee repository: sudo add-apt-repository ppa:bumblebee/stable
• Update cache from repositories: sudo apt-get update
• Install Bumblebee: sudo apt-get install bumblebee bumblebee-nvidia
• Configure Bumblebee for your user account (replace $USER with your username): sudo usermod -a -G bumblebee $USER
• Restart and relogin

Now you should have Bumblebee installed and that noisy fan silent again!