Converting ATX Power Supply to Lab Bench Power Supply
 

Small tutorial on Computer ATX Power Supplies. How to use them, how to connect them in series, in parallel. What is 12V rails? Is it possible to connect 12V rails together? ATX connector wiring explained. What is difference between old computer power supplies and new ones?
And finally how to make Lab Bench Power Supply from Computer ATX Power Supply.

http://jumperone.com/2011/06/atx-power-supply-tutorial/