I`ve run 2 cards rx480 ref with mod bios under Win 10Pro. On 1100/2200 have about 29,4 mgh on each. TDP about 140w on each card on the wall (387W with amd fx990a (AM3+) and Athlon X3 4gb ram). On of the card I started yesterday on riser x1-x1 without any additional energy. All is well over 24h. But on rig I`ll make 4 rx480ref with risers x16-x16 with add. energy. (for reliability) Great thanks to Eliovp  for his job!!!