yep, considering also your computations above it is quiet balance than 1 is to 4. have you tried checking your actual power consumptions at the wall? you can do simulations for checking.
No. I do not have the tool to calculate the actual power consumptions. But I was consult the power supply calculate tool on Internet (from AMD, and many 4rums) and I know that (the power of AMD RX 580 + riser do not pass over 220W when mining because it is used for mining, not gaming. So the power requirement is stable). An example is
https://outervision.com/power-supply-calculatorThanks a lot for your helping!..