I run 7870xt at 1100mhz (1.113v) and 750 mem for bitcoins ~505mh/s Happy medium undervolted and overclocked!
Scrypt runs poorly on these units 850mhz .981v stock mem ~410kh/s@ 20 I 16834 thread.
how are you getting 505mh/s out of it only clocked to 1100? all the ones I have Sapphires dont hit 500 till 1150mh/s