i can't help but think that advice isn't quite correct though?
for a 3700x + 1660s build, max power draw =
90w (CPU) + 140w (GPU) + 40w (components) = 270w
550w is more than sufficient
heck it's even in the fabled 40-60% efficiency zone that random people like to make up lol
I always over spec the PSU....allowing for upgrades in the future....