n0nsensical

You do not necessarily need a higher rated power supply. Not all power supplies are created equal. One manufacturer's 400 W is not the same as another manufacturer's 400 W, and even between individual models there can be large variations. The computer itself is never going to use that much power; you get one rated higher so that it has more stability while providing the lower power the computer actually needs. But if you get a quality power supply, you don't need as much headroom because it will be more stable closer to the maximum rated power than a POS power supply will ever be.

My system is very similar to the one you're planning, except I have a Radeon X850 XT PE which definitely uses more power than a single Nvidia anything under load and my power supply is "only" rated for 370 W. But I did my research and made sure it was a good 370. I seem to recall all of the power supplies you mentioned also being at least decent, so you don't need to go crazy especially if you don't plan on doing SLI. If you do plan that, then you might need to get into the 400s but even then I doubt you'd need over 500 with a good one. And you do want a good one not only so that you have more stable power but also so it's less likely to outright fail.

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