It's no breakthrough to overclock your card

More Voltage -> Volt Mod

A bios won't be able to give you more or less voltage.

It will change the timing of your ram, so you might get an increased o/c there.

Best ocing tool imo: Radlinker. Get it here: http://www28.brinkster.com/chrisww1942/
You can have settings for every single game with this thingy!
If you don't know how to do this, don't ask here, this is not the right thread.
ATITool is also really great, very useful for finding your max settings. Also has 2D/3D profiles.
I personally used a combination of ATITool / Radlinker till now on my 9700np (vmodded @437/351!!).

Forget about RedLine, Radlinker and ATITool are what you want!

Back to Topic:
many people can't overclock their card as high with 16 pipes as they did with 12 pipes.
Some people could reach their 12-pipe-max minus 5 mhz, others only 12-pipe-max minus 30 mhz.

Not something really to care about.