2 x evga tdp limited takes maybe 280W and the rest of the rig that last 50W.
Completely ignoring the PSU (in)efficiency... lol. That power has to be accounted for somewhere, as I've somewhat crudely done in horseshoes-close fashion; you just can't throw that blame all on the GPU's. Find a mythical 99.9% PSU, then there would be no wiggle room in your assertion.
Yes I ignored PSU efficiency on purpose. I am using only gold rated (90%) PSU's.