As others have said try lowering the freq.  I have one board which underperforms as well.  If I do a 'save and apply' without changing anything, sometimes it will come up good (higher hash) and sometimes it will come up bad (lower hash).  But lower freq usually means better odds of it coming up good when I restart cgminer.  I can tell within a minute if it got a good start because it will either come up past 3000 or it wont by that time.