try 1750 first, 1750 is safer , 1500 is more tight timings you are copying to higher frequency.. If 1750 brings some good improvement then you dont need 1500.
And last time I forget to mention : install amd 17.12.2 drivers , and from radeon--->gaming--global settings--change gpu workload to: compute ...and be sure it stays like that, even after restart.. This is very important..
Stop ! If it is not exactly your card, dont flash your card ! I would say more and more but here is Gateless Gate discussion topic.. You have to search and learn about bios modding little bit more..
Look this topic , you have everything to mod your bios :
https://bitcointalk.org/index.php?topic=1954245.0 and your card is ITX (mini version) , I think it is normal to expect little bit less hash rate than big brothers..
Maybe...
But. I see video youtube how guy mode this VC and have 860-900 h/s.
I try...
Use him timing...drivers 11.17.1.
Use blockchain drivers....
Max 750-760....
I save bios CPU-Z, and change timing with SRBPolarisV3-2-Int...Maybe i must change programm for change timing?