So is there a fan that will not block the ram slots if you fill up on 4 on that board?
I think the CM EVO would be fine.116 x 51 x 159 mm (4.6 x 2.0 x 6.3 in)
The XIGMATEK Gaia SD1283 should be compatible too. 120(W) x 50(D) x 159(H) mm
They're both 50mm wide cooler = the thinner the width the better for ram/dimm compatability.(dimm overhang).
Otherwise you're looking at expensive $60-80 coolers,like the Archon and Armageddon.