both afterburner and precisionX are great and used them both. just recently i am trying out nvidia inspector which also gives me the ability to change driver setting for particular games.
i have found out that krombuster that comes with AB and OC scanner that comes with pX are good for "quick and dirty" testing. heaven is good to see what affect changes make but the best test is actual gaming.
believe me, what i thought would work after a heaven bench, crashes in crysis2.