so i should ignore the "dont exceed the wattage when replacing power supply" on the motherboard spec web page?
I'd actually read that the other way. (although i would never write it that way)
Ie, from the motherboard point of view.
The wattage is simply what the power supply can supply.
The motherboard will take only what it needs.
So if the motherboard needs actually 'exceeds the wattage on the replacement power supply' then you will have an issue.
AFAIK, the voltage the power supply supplies is always the same, 12v and 5v....and they always come from your 240v. So the better power supplies with the higher wattage means its all about the current it can give off. Circuit boards drain as much current as they need and no more.