Power source wattage

[Neomega]

As I help people build computers and install windows, I get their old ones.

I have a power source, I know I need wattage of 300+

I know from information provided, I can calculate the wattage, but the wattage is not on the power source, just amps, voltage, and Hz, and I remember there is a formula.....

any one who took High School physics care to give me a quick refresher?

 

[ainwood]

Power = Voltage * Current IIRC

 

[Neomega]

Thanks, I already found it online.... however you have to divide by ROOT2... for some reason... not sure why... or if there is a
5v=22.0A
12v=7.0A
-5v=.3A
-12v=.3A

You can multiply, then add (disregarding negatives, because power is always positive)

This particular power source is 200 Watt... not powerful enough for a slot A....

 

[ainwood]

Dividing by sqrt(2) is because voltage is measured as peak voltage on an alternating current cycle. If you want to get the power, you need to use the 'average' voltage over the entire cycle. This is done by the division by sqrt(2) -> called root-mean-square (RMS) voltage / power.

If you look on stereo packages, the will quote outputs in watts, and you should always check whether the quoted value is PMPO (Peak Maximum Power Output) or RMS (root-mean-square).

re PSU: They are actually an important bit of kit! Don't get a cheap one! I suggest enermax (they are a good brand), and suggest you get about 350W.

Edit: I have this one and its great.

 

[bobgote]

PMPO in speakers (dunno if they do it for other power sources) means the amount of power its using just as it blows

anyways, you can do something i guess with 200W, but just not too much...