As you may know, CPU-G is a free and open-source CPU-Z fork that collects and displays the information about the computer it is installed on, including CPU, RAM memory, motherboard type.
The latest version available is CPU-G 0.10, which has been recently released.
In order to install CPU-G on Ubuntu, you have to add the PPA to your system, update the local repository index and install the cpu-g package:
$ sudo add-apt-repository ppa:atareao/atareao
$ sudo apt-get update
$ sudo apt-get install cpu-g
Optional, to remove cpu-g, do:
$ sudo apt-get remove cpu-g
The installation instructions should work on Ubuntu 16.04 Xenial Xerus, Ubuntu 15.10 Wily Werewolf, Ubuntu 14.04 Trusty Tahr, Linux Mint 17.x, Elementary OS 0.3 Freya and other Ubuntu derivative systems.