Power Output

[alphamonkey]

After watching the "High Wattage PSUs - Do they consume more power?" video on the LinusTechTips youtube channel I came upon a question. How does a power supply know(figurative) how much power to draw out of the wall to power a system. For example if my system takes 500 watts to power all components and I use a 1500watt power supply, how would the power supply know to use only 500watts and not take 1500 watts out of the wall.

Is there a stabilizer or method of which the power supply just reroute the excess power elsewhere.

 

It may be dumb but I am no computer expert so yeah.

It would help if anyone could explain it to me.

[sushisharkjl]

1 minute ago, alphamonkey said:

After watching the "High Wattage PSUs - Do they consume more power?" video on the LinusTechTips youtube channel I came upon a question. How does a power supply know(figurative) how much power to draw out of the wall to power a system. For example if my system takes 500 watts to power all components and I use a 1500watt power supply, how would the power supply know to use only 500watts and not take 1500 watts out of the wall.

Is there a stabilizer or method of which the power supply just reroute the excess power elsewhere.

 

It may be dumb but I am no computer expert so yeah.

It would help if anyone could explain it to me.

Think of it as a pipe.

 

The pipe is full of water, but you have only three taps through which to draw water. If you add more taps eventually the pipe won't be able to keep up.

 

It's the same thing - your PSU provides up to 1500w, but your components draw only 500w.

[Enderman]

Its just how electricity works

when you power something with constant voltage (which is what your house has) it will only draw the necessary amps due to internal resistance.

If your PC components had 0 resistance (aka a short) it would draw infinite amps and burn up your PSU or trigger a breaker)

Since all components have resistance, they will draw current less than infinite

The PSU just converts from AC to DC so if the PC components only need 500W DC, the PSU will only draw 500W AC (plus a bit extra for inefficiency)

 

Since watts =A*V then you get a constant wattage use that is less than the max wattage

[alphamonkey]

4 minutes ago, sushisharkjl said:

Think of it as a pipe.

 

The pipe is full of water, but you have only three taps through which to draw water. If you add more taps eventually the pipe won't be able to keep up.

 

It's the same thing - your PSU provides up to 1500w, but your components draw only 500w.

I agree, however how would the power supply know before hand if the power required is 500watts or more or less.

 

1 minute ago, Enderman said:

Its just how electricity works

when you power something with constant voltage (which is what your house has) it will only draw the necessary amps due to internal resistance.

If your PC components had 0 resistance (aka a short) it would draw infinite amps and burn up your PSU or trigger a breaker)

Since all components have resistance, they will draw current less than infinite

The PSU just converts from AC to DC so if the PC components only need 500W DC, the PSU will only draw 500W AC (plus a bit extra for inefficiency)

 

Since watts =A*V then you get a constant wattage use that is less than the max wattage

I agree, however how would the power supply know before hand if the power required is 500watts or more or less.

[sushisharkjl]

Just now, alphamonkey said:

I agree, however how would the power supply know before hand if the power required is 500watts or more or less.

 

I agree, however how would the power supply know before hand if the power required is 500watts or more or less.

It doesn't.

It's capable of drawing up to 1500w from the wall. 

Your components draw from the PSU, and they can draw up to 1500w total.

The PSU doesn't know anything, it just provides however much energy the components ask for.

[Enderman]

34 minutes ago, alphamonkey said:

I agree, however how would the power supply know before hand if the power required is 500watts or more or less.

it doesnt need to know

think of the power supply as just a regular wire

the stuff that goes in depends on how much is being pulled from the other end of the wire (your PC components) plus efficiency losses