[Studio Dweller]

I stand corrected. I was going on info from another Pro Tools user who received their new Mac Pro before me who told me that the adapter cables were necessary. After taking some pics of the connections and cables, I pulled out the box from the HDX card and realized that the other power cable included with the HDX card indeed fits the connection on the motherboard. I just installed that cable, fired up Pro Tools and it's working fine. No adapter required. Sorry for the misinformation and thanks for prompting me to look into this. Going to return this $70 set of adapter cables.