you could go watercooled, small cooler like a scythe big shuriken or something with long heatpipes like a noctua NH-C12P if i clears your case.
just go to the website u use for parts and take whatever cools the best and makes least noice, than look at the size and see if it would fit.
EDIT: forget the noctua's or anything big, your psu is in the way