Why can't we draw power straight from line power?

[Dubskee]

Hey guys,

 

I just had a random thought... after doing some research for a new PSU, i was wondering.. why don't our cases just have a power adaptor from the wall socket, and use power as needed, instead of using a power supply?

 

Sorry if this is a noob question, just seems like a really good idea to me

[Maskot]

Because each component requires a certain wattage....

[T.Vengeance]

Power adapters, like ones you use to charge your phone can't supply enough power to the computer. Those are 5-30W range adapers. It's no where near the power needed to power a desktop.

[_ASSASSIN_]

you have to convert from AC to DC or the other way around

[GeTecknics]

Hey guys,

 

I just had a random thought... after doing some research for a new PSU, i was wondering.. why don't our cases just have a power adaptor from the wall socket, and use power as needed, instead of using a power supply?

 

Sorry if this is a noob question, just seems like a really good idea to me

because we need to convert from ac to dc and regulate the power to make sure that the power going to it is the correct voltage/wattage to prevent too much from going into a specific part at once also the psu can use the energy more efficiently  

[the_devil52]

The electricity coming from your wall is alternating current (AC) however your computer needs direct current (DC). It's the power supplies job to convert from AC to DC. Also the electricity from the wall is usually around 120-240V but that would be way too much for your components. It reduces the voltage down to (i think) 3.3, 5 and 12 volts. 

 

There are other reasons but those are the main ones.

 

EDIT: Voltages

[LogicDeifying]

We have to convert.

[pravarth]

A PSU is basically a power adapter, except it is highy powered and converts to 12v and 5v. Your tradition power adapters which you use for a phone may output 1A at 5V, ie 5W. A laptop adapter is a bit powerful output around 90W. But computer PSU's need to handle more power (300W +) and hence bulky. 

 

At the basic level this is the main difference, technically there might be some variation, I'm no electrical engineer

[Guest]

It has nothing to do with the wattage from the wall but instead because of the fact that line voltage is AC whereas PC's run off DC current as do alsmost all electronic devices (phones, MP3's etc). If we did manage to run PC's off AC, major upgrades would be needed to be made to the power input on the parts as they would have to compensate for circuit protection etc + step down 240/120 to 12, 5 and 3.3 volts.

[TheMissxu]

Voltage is probably the main issue, but the simple fact that each component needs it's own power cable, you'd need like 6 outlets (and say good bye when a power surge comes)

[Harvey]

First watch this:

 

There is a lot going on and they explain some of it if you watch the whole thing.