Outside of trying to position the fan higher on the cooler there's a couple things. You can try to mount the fan on the opposite side of the cooler, should work even if it doesn't cool quite as well. The other options are lower profile ram as shwatzz suggested or a different cooler like the cryorig h7. It's designed with offset heatpipes to move the cooling tower (and fan) toward the back of the case away from the ram slots.