try undervolting the memory. the stock setting is 1 volt and I think my Samsungs run at 700mv and the microns at 750mv. You should notice a decent temp drop and save on some power usage.
it won't let me undervolt the memory either
What doesn't go lower in OC softwares on windows OS can easily go lower in hive OS, I think OP should consider hive OS for his AMD graphic cards, they are more happier on that OS
i will try hiveos, i will keep you posted on whether it lets me underclock/undervolt