# Power supply

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Hi al, Since I have never seen a motherboard short out. I am curios about ,what kind of effects it has. I know its 12 volt DC. Is this the same 12 volt DC in a car battery or more like a 120 volt wall plug.

a b B Homebuilt system

Not sure what you're asking. There are three components to DC electricity: voltage, current, and resistance. The voltage is the pressure that moves the electrons, the current is the moving electrons themselves, and the resistance is just what the word means--but everything has resistance and so the resistance is what the electrons are moving in. Voltage is measured in volts, current is measured in amps, and resistance is measured in ohms. Given a certain pressure (volts), only so much current (amps) will flow through a certain resistance (ohms). Raise the pressure and keep the resistance the same, and you get more current. Lower the resistance and keep the voltage the same, and you get more current. Current depends on the other two factors, but current is electrons, and there are only so many electrons a power supply can provide per second. A car battery can pump out an awesome amount of current, like 200 amps, before the voltage starts dropping, more than any desktop PSU. But PSUs don't suck, either. There's more than enough current there to cook a hot dog.

When a mobo "shorts out", anything can happen from sudden silent death with no perceptible whimper all the way up to an ear-splitting CRACK! followed by a loud BZZZZZZZ! accompanied by flames and smoke. Twelve volts at 200 amps across your hands will do nothing. Twelve volts at 200 amps across your tongue will put you in the hospital with no tongue. One hundred twenty volts across your hands can kill you. I don't even want to think about the tongue thing.

Motherboards don't short out. the power going through them does.

generalizing a power supply is simple.

you usually get a 12v transformer, the largest one in a psu, coiling to higher amps (normally 30) from 120v at whatever amps it is sucking on (10-15 is a normal house circuit, shared with everything else on it) this determines grade of power supply,

from the 12 volt transformer there is several possibilities, little 5v and even smaller 3v coils, or off to the mosfets for the 5 and 3 and APFC circuits and heatsinks sized just right for any type.

they are all quite primitive. mosfets were invented in 1929, the coils are even older ..Babble seems to make it complicated and sophisticated and even lied about to claim new technology to this very day...
A true apfc is about as smart as a new one has become. dual 12v rails single 12v rails, does not matter..that is yet another babble.

the errors happen. a tiny error is internal chip shredding. Bios is always #1, during runtime and fail, northbridge is another #1 collapser. A REAL bad "short" will burn a mosfet or inductors or caps or all of them on the mobo, and that is indeed something to see...
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