You're looking at an SXM module, so that PCB is the whole thing. TDP is 400 W. I assume these run at a sub-1 V core voltage due to their relatively low clocks, so yeah, you are looking at a core supply current that may well exceed 500 A at full load and has to be provided by those VRMs crammed on that board.

Worth pointing out that that's not really new. Gaming cards have been running at about a Volt for a bunch of years now and all of those chuck 250+ W, so the currents are rather substantial.