The cards I have are PowerColor Red Devil RX-580 Golden Sample 8GB, according to the dash-board in HiveOS, these two have Hynix memory.
This is with a modified bios which has the PBE one-click patch applied and then the bios modded to increase the memory clock to 2250MHz (I couldn't get the software (Claymore v11.0) to increase clocks for some reason it wouldn't apply (cclock/mclock), so had to do it in the bios)
Also in my experience the Win 10 would deliver 940 at those clocks with two threads. Two threads just doesn't help in linux. At least it didn't work for me.