Thank you for your replies. What I did was installed this older driver: 16.11.3-nov8. Then I disabled automatic driver updates on windows and through AMD. Followed the BIOS settings posted by z92747392. And then the final trick was this. I tried from the beginning with just my one card plugged into the PCIex16 slot. Booted up and noticed it hung at Windows load as usual but I decided to let it do its thing. After the screen turned on and off like 6 times, it stopped and it was stable and this was the first time I had a card be read from this slot. I then restarted with 2 cards, then 3 and onwards until all six. Then I was getting a BSOD.

I uninstalled the AMD drivers and rebooted. I plugged in the last card just to see, and it was recognized by Windows. I then used the AMD cleaner utility and then installed 16.9.2 from guru3d. Unbelievably it now works. Getting about 24m/hs on ethereum and 4400 on decred.

So I guess it boils down to installation methodology. For this board, that driver works. You should install windows 10 with all 6 cards attached and use that driver. Would have saved me a day, but oh well.

On to overclocking! Please share if anyone has a good writeup. The one I found was for the nitro + which I do not have. I have the nitro 8gb non plus (samsung though).