Is there a V-core mod for Voodoo5 5500 ?

[Hiero]

Some time ago I saw a modded Voodoo5 5500 on ebay. Something was changed so that the card had a higher voltage. That makes the card more overclockable on the one hand and on the other the average fps are getting better even with no overclocking.
That was also confirmed by other people who did the mod to their NV cards. How can this mod be done ? Which transistor(?) has to changed or what has to be done ?