10 Amps from the wall (standard home curcit) Powersupply with 85+ Amps

[skippytheturtle]

Most homes in the US are wired for 110 volts at 10 or 15 Amps per circuit. I am looking at power supplies with 80 or more amps available on the 12 volt rail. How is this possible? Where do these amps come from?

 

Thanks 

[Terminashunator]

110v @ 10 amps is ~1100w.

 

Typically, a 1100w PSU isn't fully utilized, and they're not commonly maxed out anyways.

 

The watts don't "come" from anywhere. You pull as much as the breaker allows, and if you go over that limit, you pop the breaker.

 

Ryan Schrout(sp?) from PCPer was having a problem testing dual R9 295x2 because he was popping the breaker at his lab. That, and he needed a 1500w PSU.

[Guest]

A PSU may provide 80A, yes, but it will do so with 12V, for example. Wattage = Voltage x Amperage. If you decrease the voltage you can increase the current. It's actually not as simple as that because there is a difference between AC and DC but that is the gist of it.

[Terminashunator]

A PSU may provide 80A, yes, but it will do so with 12V, for example. Wattage = Voltage x Amperage. If you decrease the voltage you can increase the current.

Yes, you can do magical changes with AC power. 120V at 10A is the same 1200w as 12V at 100A. Volts Times Amps = Watts.

[TheDigitalRealm]

Your power supply converts the output from the wall socket.

The equation for voltage, resistance and Current is V=IxR (I being Current)

Power(watts) = Voltage x Current so all one needs to do is increase one of the values in the above equation to increase the 'Power' output.

[skippytheturtle]

That was a lot of replies for a cryptic title

 

I knew watts = volts x amps, but didn't know it was possible to exchange volts for amps.

 

Thanks everyone! You made it easy to understand

[Guest]

That was a lot of replies for a cryptic title

 

I knew watts = volts x amps, but didn't know it was possible to exchange volts for amps.

 

Thanks everyone! You made it easy to understand

 

That's actually the point of the PSU (besides converting AC to DC power), you wouldn't want to feed your PC power at 120V.

[skippytheturtle]

It would be more efficient wouldnt int

 

you wouldn't want to feed your PC power at 120V.

 

Wouldn't that make it more efficient if PCs were made to run at a higher voltage? 

Higher voltage means less resistance on overhead lines and such.

 

thanks 

[lbrwnie]

It would be more efficient wouldnt int

 

 

Wouldn't that make it more efficient if PCs were made to run at a higher voltage? 

Higher voltage means less resistance on overhead lines and such.

 

thanks 

Than there is not enough amps for much to run, most power supplies find a balance of what computers usually need. I don't know enough to tell you wether they would be more efficient but it would certainly reduce the amount of amps going into your computer and reduce what stuff you could run off of that psu.

[Terminashunator]

Than there is not enough amps for much to run, most power supplies find a balance of what computers usually need. I don't know enough to tell you wether they would be more efficient but it would certainly reduce the amount of amps going into your computer and reduce what stuff you could run off of that psu.

The amount of power lost, efficiency wise, is pretty low for most power supplies.

 

Consider an 80+ power supply, at 50% load or higher, is about 80% efficient with 20% being lost as heat.

[skippytheturtle]

Thanks everyone 

 

I wish we used 220v or what ever a lot of the world uses. That would be a bit more efficient at the wall. Some data centers here in the states use higher volts "from the wall" to the PSU.

[lachyman]

To put this into a simple physics theory, a PSU first uses a transformator to transform the 110/230V current into 12V while increasing the amperage. Then it uses a diode with capacitors to change AC from the wall into a pulsating current that is pretty much DC with usually <2% voltage alteration every period.

[juretrn]

That was a lot of replies for a cryptic title

 

I knew watts = volts x amps, but didn't know it was possible to exchange volts for amps.

 

Thanks everyone! You made it easy to understand

It's called a transformer! (On the PSU side, you also need a rectifier to get DC from AC.

 

It would be more efficient wouldnt int

 

 

Wouldn't that make it more efficient if PCs were made to run at a higher voltage? 

Higher voltage means less resistance on overhead lines and such.

 

thanks 

NO

Electronics is more efficient at low voltages.