i have a similar board, with the same bridge heatsink and fan, after a few weeks, it started making the most annoying humming noise, later boards by asus have since eliminated the heatink and fan for this reason. I would recommend getting a replacement heatsink for it
http://www.newegg.com/Product/Produc...82E16835108072
i have the earlier version of this heatsink fan in my box and its nice and silent.