AHCI is the acronym for the Advanced Host Controller Interface. It is a new interface specification that allows the SATA controller driver to support advanced features like Native Command Queuing and Hot Plug.
The System applet provides access to general system properties. You also can open the System
applet by right-clicking Computer and choosing Properties. The first page of the System property applet provides basic information about your system, including OS version, installed memory, CPU type, and registration information.
Bad memory can manifest itself in anything from frequent error messages and crashes to your system simply not starting. Errors in your computers memory (RAM) aren't always consistent, either; they can be intermittent and can get worse over time.
Problems might also occur after you install Ubuntu. This section addresses several possible postinstallation problems. This section covers only problems that appear immediately after installation - those that prevent Ubuntu from working correctly immediately after its first boot.