I will be putting together a PC. How do I determine thePower Supply
wattage needed?
You don't. Wattages are speced like cough medicine. A supply rated
at 230 watts from a responsible manufacturer could also be speced at
325 watts by one hyping a product only on watts and dollars. They
just forget to mention what they are measuring.
Determine the current rating for each voltage of each peripheral -
and then sum up that current. Then review a supply's current for each
voltage. Supply must meet or exceed that current rating.
Then you move on the other essential fact: does it come with a long
list of numeric specifications? If not, then what else are they
'forgetting' to include in a supply. The functions performed by a
supply are quite numerous. Many essential functions are 'forgotten'
when selling to computer assemblers where knowledge of electricity was
not required to become certified.
Sum up current consumption for each voltage. Verify that nearly a
full page of numeric specs are provided. Suddenly many supplies no
longer make the cut.