An axial flow fan includes blades mounted on a hub and extending radially outward to a shroud disposed around the hub. Pairs of stators are connected to the shroud at positions angularly spaced about the inner periphery of the shroud. Each pair of stators includes a trailing stator angularly spaced from a leading stator by a distance related to the number of blades of the cooling fan. A trailing stator of one pair is spaced from a leading stator of an adjacent pair by a distance different than the distance between leading and trailing stators of each pair.