So, I'm building a prusa i3 with iduino mega R3+ramps 1.4 and I'm in the "wiring" section of the building instructions. But I can't figure out the need to connect the fans to the PSU. According to the wiki or the PDF, I'm supposed to get the wiring connect either to the PSU directly, or to the board power port.

But i'm confused, because in this picture

Is there a way to connect both fans into the board somewhere ? Am I really supposed to connect the fans to the PSU or the board power port ?
Thank you all in advance for your help !