I have been trying to flash the bios with lower voltages, but they dont seem to work, do you have any idea what voltage selection i should be using?
1080 mV as starting point, but some chips can go as low as 950 mV. For example
1075 mV -> 1100 Mhz
1050 mV -> 1050 Mhz
1020 mV -> 1000 Mhz
980 mV -> 950 Mhz
Currently I have:
7870XT: Tahiti LE : 0.95V -> 1000 Mhz
R9-270:Pitcairn: 1.05V -> 1100 Mhz
7970: Tahiti: 1.05V -> 1030 Mhz (too high voltage, but needed for MemoryCoin and VertCoin)
6950: Cayman: 1.1V -> 900 Mhz
Of course, the lower voltage you can reach for the particular core clock that maximizes hash rate, the better