When you start up the computer with Ubuntu duel booted you can select memory test; and it tests the RAM memory installed for errors. Two of the 1 Gigabyte RAM memories on my computer are made by OCZ, and they are used for gamers and for sophisticated type computer programs; because, the OCZ RAM has better performance and stability.
There is a another computer free operating system called Debian OS. Debian is similar to Ubuntu; but Ubuntu uses a a user interface, with GNU/Linux.
Many developers are building different programs for Ubuntu and Debian; but many of the programs developed are sometimes almost same. Ubuntu, was made more for inexperienced first time users; so, Ubuntu is called “Linux for human beings”. There are now over 20 million Ubuntu users altogether; in 2015.
Debian can be downloaded for free, at; Debian -- The Universal Operating System.
The Debian; requires more knowledge of Linux, to use the operating system. Both; Ubuntu and Debian, are almost completely computer virus free.
Debian Linux Gnome Desktop Tutorial
Debian Tutorial - First steps - Adding Repos / Flash / Codecs
Important Linux Commands : Tutorial # 5
Linux Mint 17.1 Best so far.
Debian vs. Ubuntu: Which is the Right Linux Distribution for You?
Debian vs. Ubuntu vs. Linux Mint: Which Distribution Should You Use?
Understanding linux basic commands Part1 - One of the Best Video
Understanding linux basic commands Part2 - One of the Best Video
Understanding Linux directory structure - One of the Best Video