Ive done a search on guru3d
and what i found is, its really possible to unlock the 4 pipelines and raise the core/mem clocks to the level of the 6600.
BUT, it has to be the NV43 revision A2 chipset, neither the NV43 A4 nor the NV44 can do this.
In others words, only one AGP version of this, it can be done. The newer versions of the AGP, and all PCI-X cant...
Im not buying mine from a store, but from a service like ebay here, mercadolivre.com.br
, so the guy just tested the card for me and assured its a NV43 A2.
So be warned....