Check for a possible grounded board, make sure all screw points are on standoff properly or mounted securely without touching the case. If all appears correctly, pull the board out of the case and power it up on an anti static mat (if no mat is available, laying the bag it came in out flat on a table will work fine) to see if it will fire and rule out the case completely. Try both of your PSUs if the first doesnt fire. Are both PSUs KNOWN good, ie have seen them power on successfully in another system?
All else fails, there must be an issue with the board or it's hooked up improperly (not likely but possible).