is it possible to softmod the voltage on a gf 6800xt?

as of the title, is there a way to increase voltage on a gf 6800xt card without the use of a soldering device (not hardware mod)?
mine is a galaxy one, running on pci-e. I wan to kno if its possible to increase the voltage using software so tht oc can be increase further. Mine can oc from 400 to 480, any higher there'll be artifact. The temp is around 63-65 under load, I tot temp wouldn't be a limiting factor for the oc cos its still not too high. But after i reapply a thinner paste, the temp goes down to 57/58 under load. Havent tried oc at this lower temp but i guess artifact still creeps in at over 480.
Anyway, any advise on overvolting the software way on gf6800xt?
I cant find any after searching but im a very much still noob compare to most of u guys out there. Thanks in advance. ;-)