Now Sapphires site doesn't actually say TDP(and rightly so) they call it power power consumption. 135w is likely the average at 100% usage but there can be spikes above that(transient loads) they went from being limited to 150w(slot+6-pin) to 225w(slot +8 pin) for extra padding for transients and potentially further overclocking without the possibility of having to go out of spec on the slot or cable.
AMD recommends a minimum 450 Watts PSU for this GPU when used in any Gaming rig. That number is not fake. Its power consumption presumably under full load.
The Typical Board Power (Desktop) of this card is 130 Watts.
Now Sapphires site doesn't actually say TDP(and rightly so) they call it power power consumption. 135w is likely the average at 100% usage but there can be spikes above that(transient loads) they went from being limited to 150w(slot+6-pin) to 225w(slot +8 pin) for extra padding for transients and potentially further overclocking without the possibility of having to go out of spec on the slot or cable.