The Radeon RX 480 significantly exceeds its official TDP. Moreover, distribution between the motherboard’s PCIe slot and the auxiliary power connector isn't optimal either. It’s up to AMD’s partners to design cards without these shortcomings.
With Tom's Hardware reporting that the RX 480 draws (substantailly) more than the 75W allowed from the motherboard (for example, the PCI Express high-power card spec allows a mazimum of 66W to be drawn from the 12V pins of the PCI Express slot, and the RX 480 averages 79W from the 12V lines alone) AMD seems to be violating the PCI Express(R) spec. Of course, I'd love to see HardOCP try to duplicate Tom's results.