For those manuals I have read (Abit,Asus,Tyan,Epox,Soyo,MSI) they were all lacking in proper explanations of a whole lot of things and as a result I have used the internet resources to get meaningful explanations of various settings. Therefore I would say none - both support and manuals. Now if they wrote in "English" then I may think differently.
Hey where do you think the boards are manufactured primarily!