Havent read the entire thread, but isnt 750W a bit low? That CPU alone at that clock could be pulling 150-160W at stock voltage (and possibly considerably more if you overvolted it). Add the motherboard, RAM, water pump, fans, and you are probably >200W, leaving 550W for the three cards. YOu dont mention overclocking the GPUs, but even at stock speeds thats cutting it close IMO.