How does power supply wattage work?

[BazeleyBoy]

Hello, I am somewhat confused about how power supplies work. I'm right in thinking that a "500W PSU" can give a maximum amount of 500 watts to a component, and gives the others the appropriate amount? or does the 500W mean that if you add up the amount that each part of the pc is using and it reaches 500 or less, then a 500W power supply is ok for the system?
I am thinking of getting the amd phenom ii x4 965 Black Edition and overclocking it, although this is my first build.
If anyone can help with my question that would be great

Thanks

 

[FinneousPJ]

Good quality PSUs will feature the maximum continuous wattage. This means your latter idea is more correct, although a good unit won't break if you draw more power for a short time.

 

[casper1973]

"if you add up the amount that each part of the pc is using and it reaches 500 or less, then a 500W power supply is ok"

This part is correct(ish).
Ideally when you add up the wattage of all your components you don't want it to exceed 80% of the total wattage available. This helps with efficiency and protects you from any sudden surges in demand that might push it over the limit.

 

[qwerty_ashu]

but what about the amperage on +12V rail & +5V rail requirement ???

 

[FinneousPJ]

What about that?

 

[toyftw]

Hello, I am somewhat confused about how power supplies work. I'm right in thinking that a "500W PSU" can give a maximum amount of 500 watts to a component, and gives the others the appropriate amount? or does the 500W mean that if you add up the amount that each part of the pc is using and it reaches 500 or less, then a 500W power supply is ok for the system?
I am thinking of getting the amd phenom ii x4 965 Black Edition and overclocking it, although this is my first build.
If anyone can help with my question that would be great

Thanks

Hi - The wattage rating of the PSU is typically the total power output
(all rails)of the unit.
Better quality bramds are conservative in their ratings,
and their units sometimes exceed the publ ratings.

On the other hand there are many poor quality inits from
many brands that don't deliver the publ specs, sometimes by
an alarming difference.

The key when you shop for a PSU is to 1st select a quality brand.
Quality brands: Seasonic, XFX, PC P&Coolong, Rosewill Capstone series,
most Corsair's, most Antec's, Enermax, & some others.

Tom

 

[Brett928S2]

Hi

Look up OHMS LAW ...

All the best Brett