Some years ago a friend of mine bought a "bespoke" PC which was reckoned to be exceptionally fast etc. It wasn't as impressive as he expected, and after a couple of years it stopped working. The manufacturer advised him to replace it with a new one, and sent him a suggested spec, which he showed to me.
It was all very upmarket, except for a 300 watt power supply. I reckoned it needed more like 800 watts. He challenged the manufacturer who got quite indignant.
I had a spare 500 watt power supply in my cupboard, so tried replacing the one in his failed PC (which turned out to be 300 watt). That got the machine working better than ever before, and it's still in use. I calculated that it needed all 500 watts. We later fitted an 800 watt PSU.