+12v2 rail

[wxt38]

i know nowadays dual rail PSU are plenty and i know the first rail in dual rail psu goes to the 2x2 connector to supply the cpu and senitive devices and second rail goes to the rest. but i've never seen where the second rail goes (+12v2). i been googling it for hours and no results so could some one post a pic or two that has the second rail and the place where it goes. or describe fully about it.

 

[Flanker]

The rails aren't physical objects. The 20/24-pin connectors supply power to the whole motherboard.