i got 3 card Palit HD 4870 and all of them do 900 mhz stable @ 1.4-1.5v , the best one did 980 Mhz under water with 1.6v and passed 3d mark vantage , all those card are sold now i keep my old HD 4870 which also rock solid @ 900 mhz , can do higher but i am already happy with the current result
@Blazing fire

And how does one change and monitor the voltage, like makaka did
I jsut plugged a multimeter to the card and changed the VR ,