i have little knowledge of the fx 5700 series, i really begin my knowledge of overclocking in the fx series at the fx 5800u.
there is a program like ati tool called coolbits. it's actually just a registry patch that enables features that are made by nvidia and come with the drivers (such as the ability to overclock, but certainly not limited to that).
you can find coolbits here:
<-- the manual "i'm a geek" way
<-- the automagic "i'm a lazy geek" way (my personal preference, lol) suggest this page for many other useful applications that go along with tweaking and overclocking your video card
good luck... the auto detect is only good for ballpark estimates; usually you can overclock higher than the auto detect thinks you can.