The OP was devoid of any sort of analysis of power supply being stressed such as drooping voltage or current under load, etc. Which supports the idea that it was merely a fishing expedition to sell unneeded power supplies for the Mac Mini. You can easily tell when a mini goes from 'working hard' to 'approaching maximum' by the sound of the cooling fan as it slows down slightly. That is the clue to start monitoring voltages and currents supplied by the PS. My Mac PSs never get more than warm and I doubt they would ever prove inadequate. Any limitations would derive from the mini itself and would depend on its instantaneous loading and its ability to shed chores in response.
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