It is the same card, but don't take my word for it.
You can check the BIOS name in the upper right corner of Hawaii Bios Reader to be sure.
I will tell you a secret.
In Hawaii Bios Reader if you click on VRM settings and there is a table with an entry which says 0x8D VDDC Offset, then you are in luck.
Because here you can enter a voltage offset that will apply to all DPM states from 1 to 7.
If you would like an undervolt of, say -100mV, then you would enter a value of 65520.
If you need a different voltage and are not sure where the above value was derived, then PM me.
If you do this, then leave the voltage values untouched in the PowerPlay and LimitTables.
This will work only if Hawai Bios editor shows a table, which it does for my Sapphire Nitro cards.
Be sure to read the red text above the table and be sure you know what you are doing.
I tried the 1100 option and i got black screened in start up.... Sapphire NITRO R9 390 TRI_X 8gb
Anybody has a MODDED working bios?