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When I open the switch of the power supply, the Computer automatically starts up and then in three seconds automatically shuts down.

I have tried shutting down windows properly but this unusual behaviour is still there.

The Vendor says this is normal! but how can that be?

Whenever I switch on the UPS/Power Supply the computer starts and shuts down which might some day cause any hardware to go bad!

How to prevent this?

Edit: There is NO Power loss.

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u cant. thats a normal behavior made by wired-logic in the power supply itself. u can buy a used old but a good premium category PS without this feature. e.g. ENERMAX. (i am using a 10years old one right now) u might need some very cheap MOLEX>>SATA adapters for newer HDDs,SSDs. make sure the output power matches the one u r using. if u can find one hiding in a warehouse 8-10years ago unused, buy that. if u r buying a heavily used one take it to an operator and have him replacing old elco capacitors on the PCB. then u can use it for long years and get rid of that feature. – user120568 Feb 28 '12 at 21:55
up vote 4 down vote accepted

What you have described is normal behavior when newer model power supplies are plugged into power or switched on using the switch on the power supply itself. This does not actually turn the computer on, it's more of a self test. It should not damage the computer.

You said you are using a UPS. When you turn it on, it has the same effect as plugging the computer into a power outlet.

In order to prevent this from happening, leave the UPS on. Desktop computers today are meant to be left plugged in.

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if you are right, is there a way i can stop this SELF TEST? Its well annoying for a few. – Doopy Doo Feb 9 '12 at 14:55
cannot let the computer remain plugged in because of children.. – Doopy Doo Feb 9 '12 at 14:58
Sorry. If you choose to unplug it, you will have to live with it acting that way. Why does it need to be unplugged because of children? If you are trying to restrict access, there are other options. – CharlieRB Feb 9 '12 at 15:05
okay thanks.... – Doopy Doo Feb 9 '12 at 15:09
> If you are trying to restrict access, there are other options. Indeed. An easy option, depending on your motherboard, would be to disable the power-switch (on the case physically or via the BIOS) and instead set the BIOS to use a hotkey or password typed on the keyboard to turn it on. – Synetech Feb 28 '12 at 22:31

If my understanding is correct, which I'm not certain it is, you may be able to fix this in the BIOS power settings. Set "on power loss" to "remain off".

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No there is no power loss. It happens even when the computer is shut down properly. – Doopy Doo Feb 9 '12 at 14:54
in that case @charlie's answer applies. – Sirex Feb 9 '12 at 14:56
okay but i dont want this self test. how to turn it off. and cannot let the computer remain plugged in because of children.. – Doopy Doo Feb 9 '12 at 14:57

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