I got gigabyte 7950 and i put your bios. Cannot run claymoreminer 4.0 at 1100 mhz core and 1575 mhz mem because miner says invalid data.. I change voltage to 1.200V and 1050mhz core 1450mhz mem and now it runs 75-79sol without errors.

I dont know if more voltage would change anything..
my 7970 go worse with 1100\1575. 78 vs 85 on default clocks . -i2
try to run it on defaults