power supply wrong voltage?

[fartman]

What happens when you turn on a computer with the wrong voltage setting on the power supply. Can it damage more than just the power supply? I am also wondering if a motherboard has to be grounded in order to function properly. I have heard about people testing a motherboard outside of a case. Is this possible?

[Sterling_Aug]

Nothing happens. It will not turn on and it will not damage anything.

A mobo does not need to be grounded. The power supply plug that connects to the mobo takes care of that. It is a good trouble shooting test to take the mobo out of the case and test it on a piece of cardboard.

[Kandar]

I beg to differ on this one. We have had several machines blow up with one hell of a bang after someone swapped the voltage to 110V instaed of 240V. The PSU's are destroyed beyond repair.

[Sterling_Aug]

Why are you running a power supply on 240 Volts? I would never think of running a PC on 240 VAC.

We changed power supply from 110 V to 240 V while I was in school a few years ago and nothing happened.

[Baddog]

I beg to differ on this one. We have had several machines blow up with one hell of a bang after someone swapped the voltage to 110V instead of 240V. The PSU's are destroyed beyond repair.

Switching to 110v on 240v electricity will double the voltage in UK countries.
And then you have the big bang theory.

[Sterling_Aug]

Well in the USA it doesn't hurt anything, so since fartman also lives in the US, his answer is "it will do nothing".

[Kandar]

Whats wrong with running a PC on 240V AC?

A system specifically designed to run on 240V will not run on 110V.
Reducing the Voltage from 240V > 110V increases the current flow by more than double. A 500w PSU would pull 2 Amps at 240Volts. This would jump to 4.5A on 110Volt supply.

[Sterling_Aug]

No one runs a PC on 240VAC in the US because if you do, then you risk the big bang when someone switches it back to where they expected it to be set at.

[GrefMofovich]

and if you're posting from the moon, I would recommend that you ground the motherboard, just in case...

good rule of thumb, regardless of where in the galaxy you are: if you tell a device to be expecting x volts and then give it > x volts, it may be hurt and possibly die

-GM

[Kandar]

No one runs a PC on 240VAC in the US because if you do, then you risk the big bang when someone switches it back to where they expected it to be set at.

Thats just what I was saying.
They are designed to run within a specified voltage range. If you change the range either up or down from its designed perameters you can blow it up.

[Sterling_Aug]

But if you look at every power supply made since 1981, then you will notice that every power supply has a dual voltage slide switch on the back.

All power supplies are designed to be run at either 115VAC or 240VAC depending on how you set the switch. For those living in 115 volt areas they use one setting and for those living in a 240 Volt area they set it to the other setting.

As long as you know which way to set it for the correct voltage in your area, then you are fine.

[GrefMofovich]

In other words, some pansy equipment will even manage to fry if you give too little voltage, but not computer PSU's, right? I respect computer PSU's a lot.

-GM

[Kandar]

In a nutshell it’s as simple as this:

Equipment designed to run on 240V and connected to a 240V supply will instantly and probably quite spectacularly go BANG! If you switch the PSU voltage selector switch to 110V. I have seen this happen on numerous occasion and the damage has been extensive and by no means was it restricted to just the PSU.
Equipment designed to run on 110V – 120V and connected to a 110V – 120V supply will most likely suffer too great a voltage drop to actually function at all if you were to switch the PSU voltage selector switch to 240V. I currently live in the UK where the electricity is supplied at 240V AC so I have not personally encountered a situation where switching to 240V was an issue. Doing so in other parts of the world may or may not be detrimental to the PSU or other connected components. Certainly it’s not to be recommended.

Personally I prefer auto sensing transformers that can function across a wider voltage range to suite the supply or bettter still, fixed winding transformers that are hard wired to suite the electrical supply of the country where they are intended to be sold.
Giving the end user the idea that they have a choice when actually they don’t is a recipe for disaster.