Also do not forget that your hash rate will show lower because of WU and that is what counts.  I have seen people hash to the moon speed wise, but the work submitted was much much lower than if they would tune it down to tweek other things. If I am hashing @ 2MH per with a 5-10% reject rate, where as I would get more if I would slow it down to 1.9MH with a 1% reject/stale rate.