3850 Bios limit :( ?

[Vatos_locos]

ok i got one sapphire 3850 256Mb i flashed the moded bios 770/957 vmoded the card Vgpu 1,3 and she is not passing 870Mhz even with more voltages i set the Core @ 869 and she is stable so i give 1 Mhz more and i get a black screen and the pc freezes so is there any solution yet ?

here is the Bios i 'am using the card is water cooled so the temps are not a problem 37*C on load