err, thats not how you compute efficiency based on 80+
medyo confusing ang exact explanation pero eto para mas madali
i.e. if running your 600W PSU at 100% with 81% efficiency (80+ bronze), you will draw 600W + 140W (600W / 81%) = 740W from the outlet and therefore waste 140W
although some computations put it at 600W x 19% = 114W
but whatever the correct one is, you should get the point that its not how much your PSU will output, its how much wattage is drawn and wasted by the PSU
and like I said, mga close to 400W na ang draw ng system mo WITHOUT other components plugged in that will also draw power. your PSU will only output max of 520W and over time yung ibibigay na power yan will be less and less so baka mga after a year or two, hindi na enough ang ibibigay for your system. unless you are planning to upgrade by that time anyways. ako kasi I typically build my PC to last for 3 years so kahit mga 500W lang draw ng system ko, I use 750W or higher PSU. also, usually higher rated PSU have better efficiency (80+ gold and platinum) so less waste