In my search to find the answers to some fan wiring questions I had, I came across this document. Thought it might be useful reference for somebody building, modding, or cooling a case, or someone like me who doesn?t know if they need a three or four pin tail on a fan. 
http://www.teleport.com/~atx/spec/atx2_03.pdf
For the people in the business, or other experts: Do you find that ( ?all?, ?most?, ?any? ) manufacturers adhere to the wiring voltage/color scheme of tables 8-9 on pages 27-28, or is it all on a case-by-case basis ?
http://www.teleport.com/~atx/spec/atx2_03.pdf
For the people in the business, or other experts: Do you find that ( ?all?, ?most?, ?any? ) manufacturers adhere to the wiring voltage/color scheme of tables 8-9 on pages 27-28, or is it all on a case-by-case basis ?