What is the minimum amount of power supply when a PC uses 225 watts while booting but175 watts when running?

Answer 1

Personally, I wouldn't use less than a 300 Watt power supply in that situation.

But then, I never use less than a 500 Watt power supply when replacing a power supply or building a computer.

The advantage is, the larger power supply can easily handle the load and will not run as hot. Since electronic components typically fail more rapidly when they get hot, the larger power supply will usually last much longer.

But that's just a suggestion.