Dont copy and paste information, hoping to get an upvote. It's not fair on other users! People put time and effort into doing research and writing their own informative article.
I copied this section and googled it:
Many manufacturers have experimented with different levels of integration, building in some or even all of these components. However, there are drawbacks. It’s harder to upgrade the specification if integrated components can’t be removed, and at first highly integrated motherboards often required non-standard cases.
And I found you took it from somewhere like here:
http://www.oocities.org/media_h/Technology/Documentations/System_Boards_Technical_Details.htm