On Gainward GTX 460 1GB GLH( 800/1600/4000) it's posible to adjust GPU voltage, and most probably on Palit GTX 460 PLATINIUM(same clocks, same PCB, a little different cage cooler) because Gainward is a subvendor of Palit.
But all GTX 460 with ON NCP 5388 can adjust voltge with MSI Afterburner1.61 normaly.
Gigabyte 460OC 1gb can to.