> 2) Still may run a dual PSU, but with the CPU below and the cards at 1200W i'd max at around 1600W, add overhead, and there are some 2000W PSUs that could do it. Also being on 240v mains makes this easier on the PSU selection as I have seen many can source more wattage when on 230/240 vs 115/120.
One suggestion, also limit clock speeds/voltages. There are transients when the 3090 loads models that can exceed double their typical draw, 4 starting at once can draw substantially more than I expected.
One suggestion, also limit clock speeds/voltages. There are transients when the 3090 loads models that can exceed double their typical draw, 4 starting at once can draw substantially more than I expected.