yoongkc

Given that the PSU can supply up to a certain amount of power, and since all the power outlet has to be same for every plug, i.e., the plug to every harddisk and dvd drive should be the same, am I right to say that a 550W PSU has more cables than a 450W PSU?

If not, then where do the extra power comes from to support the additional 100W?

Timo

Well, not specifically.

Watt = Amperage times volts (A*V=Watts)

So to deliver more watts you only have to put more amps over a certain wire (or a higher voltage, but that is out of the question with a computer :p except with overclocking which is done in the bios and on the mobo etc.).

In general a higher wattage PSU means it has more +12 volt rails seeing those are the driving forces behind your Graphic card(s) and hard disk(s) (and more if you want/will). But they only add more +12V rails so that each individual rail can deliver a good voltage with those amps. Because if you have one +12V rail that runs like 60amps and +12V the voltage will most likely drop a bit when you start using a lot of those amps (although good PSU's won't do this, but they cost a fortune).

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Ordered and in the making (the current one isn't worthy to be mentioned): Clicky here
Mobo: XFX 680i LT Sli
CPU: Q6600
Vcard: 2x 8800GT Sli
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yoongkc

So am I right to say that the PSU will supply the voltage accordingly? As in, if the whole system needs 400W, it will just supply 400W, and if the system requires 500W, it will increase it's output power accordingly?

If so, what actually controls the output of the system? The rails will probably needs some "conditions" to determine the supply voltage right?

oscaryu1

Yes.

All you need to know is whether you have enough power. The motherboard will do the rest

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