I've tested Eliovp's rom on 380X (GV-R938XG1)

GPU shows 21.3 MH with an official rom
With a new rom I've got 22.9 MH (Memory Clock 1650)
Though the system is unstable and there were couple reboots and driver crashes.

I ended up with Memory Clock 1600 and 22.6 MH so I'm going to see GPU performance with these settings for a while.