My best scenario is like this, 12 GPU RX 5xx 1300w on wall with PSU 1000+850/750 (1000w for 7 gpu + system and 750w for 5 gpu), 13 doable but 2 last card hashrate halved. Do not use that adrenaline drive, use 17.11.4 and don't forget to change mod from graphic to compute for each card. At 1st, windows will only detect 7 but after you install driver it will show all your GPU. And you need to mod your GPU bios so you can get lower watt and higher hashrate. You can read at forum how to get it or maybe ask your friend to do it for you using teamviewer.
Thanks for the help. I will try that 17.11.4 and check again.