It isn't just the ATX PSU.  If a chip operates at 0.55 J/GH how are you going to power it?  Plug 12V connector from power supply to it and blow it up?  Most ASICs run at 1V.  ATX doesn't supply 1V.  So you need a DC to DC PSU to convert 12V to 1V.  Good ones are roughly 90% efficient.  So the wattage for the ASIC boards are going to be >0.55 J/GH even if the chip is 0.55 J/GH.  Now how are you going to cool up to 1400W of heat? Fans consume wattage, as does the system controller.  So the overall DC system wattage is higher than the board wattage which is higher than the chip wattage.  Now to convert AC to DC you are talking another ~10% inefficiency so the AC wattage is even higher.

Still it looks like you just assumed everything is operating at 0.7 J/GH.  That ignores the petahashes of existing hardware which is much less efficiency. Long before you get to 200 PH/s for example every 55nm or higher chip will be operating with negative gross margin.  Why would they continue to mine to turn $100 in electricity into $50 in Bitcoins?  Simple they won't and when they go idle it will slow the growth of the network.

200 PH/s isn't any more realistic.  It assumes that all existing hardware goes into the trashcan and despite hashrate already being so high that the break even point (even assumming no more hashrate growth) is years in the future people keep buying more and more rigs month after month until they are negative ROI% from day 1.