fan to keep ramps cool (duh!) (no replies)

where does one connect a fan on a ramps 1.4 ? .. NOT the 12V between the bed heater and hot end (i plan on useing that for the fan on the X-carrige for bridges and such) , but another 12 OR 5 v fan power so i can blow air accross the board at a constant speed. (i'm thinking either will work , i'm just going to run down the road to the computer place and grab a vid card fan and i know they will run on either just differnt speeds)

EDIT: ok after about 10 mins of not thinking about it , i now know i'm and idiot :) .. i'm useing a pc porwesupply to power the unit wich = LOTS of power connectors ..