Installation from scratch

When installing ubuntu from my usb key it simply froze after setup. I had to enter in maintenance mode, log as root and the resume to get a VGA screen. After that I was able to install the nvidia drivers by folowing the steps the folowing steps

Turning in nvidia mode

The command sudo prime-select nvidia followed by a reboot makes use of the nvidia chipset. As a result, the powertop tool show a use of 15W.

Turning intel mode

The command sudo prime-select intel followed by a reboot makes use of the intel chipset. However a bug introduced with 18.04 makes both nvidia and intel running and it uses 20W and worst did not allow to shutdown/reboot/suspend/hibernate. I ended up by using that solution which reduce to 7W. Note that I had to make sure the grub was nouveau.modeset=0 nouveau.runpm=0 in the /etc/default/grub file. After installed the tlp tool I ended up using 5W.

Note that I tried that other solution but this resulted in system freeze at reboot.