Hi all .
I'm new to mining but have learnt fast from reading through all these forums so thanks all for the great comments shared.
There are so many choices to be made and I guess finding the best solution is what it is all about.
I purchased 3 x Sapphire RX470 4GB OC card (Hynix) for $200 each.
Struggled to set them up in the beginning but they are now running stable.

Downloaded claymore's miner. Didn't change or enter any settings, just add an ether pool and a Sia pool with wallet address.
Cards apprear to be overclocked already at 1750.
Current speed on dual mining is 20.5Mh per card on Eth and 310Mh per card on Sia.
If I mine only Eth then 22.2Mh per card.
Power draw on Powertech GPUZ fluctuates between 85w to 95w per card.
Have not tested at wall yet.
Tested now with meter at the wall and power draw is a whopping 570w for complete setup. Ouch!!

It seems there are ways to mess around with the bios and get better speeds but is it really worth it ?
If I could get the Mh rate up at what extra cost of electricity etc.. taking into account potentially bricking a card and losing warranties etc..
Another thing to take into account is the amount of downtime while messing around with these settings.

Has any one got an easy to follow guide or a modded bios for this particular card and what would your advice be on overclocking it considering it is an already overclocked card.
Sapphire RX470 4GB OC card (Hynix)

Another question is whether it is better to dual mine Eth and Sia or just only mine Eth considering the difference in speeds above ?

Thanks in advance