you can edit the bios to mod the voltage, using software like NiBiTor v2.6, which found in here:http://www.mvktech.net/component/opt...cat,92/page,2/
after editing bios and i finally got up to 526/1228, it is my max. (fan speed @ 86%) hitting 69C when it runs ATI tool
on 1.4v, 495/1197 is the max. and scored 7840 on 3D mark 05.
i think the silencer is holding me back (it just performs little bit better than stock HS and exhaust the hot air to the back of the case, if you got a good airflow case, then it is not needed), Zalman would be better choice if you like to push the card further. of coz water cooling is a different world.