I have a Cooler Master 212EVO on it now, dropped idle temps from 38C or so to the mid 20's. I first used just one fan then added the second one and made zero difference in temp, idle and load.
My Sandy's temp spread is 16C under IBT. I think it's because I let it get to 100C once. Otherwise it still runs well.
Oh, I did run Prim95 14.5 hours on Haswell at 4.2GHz with no errors and max temp was 69C, I'm happy with that.