You didn't install it correctly otherwise it would not have fried your mobo
I installed 'it' correctly, it was in my rushed process of putting everything else back together that I either shorted the board with dust or static. Or maybe I needed an excuse to upgrade. Anyway.....
I just looked and I had my PSU incorrect it's a rosewill xtream RX850-S-B so its 850W not 750W.