Tom's Hardware > Forum > CPU & Components > Power Supplies, PC Cases & Case Mods > PSU turns on when plugged into power cable

PSU turns on when plugged into power cable

Forum CPU & Components : Power Supplies, PC Cases & Case Mods - PSU turns on when plugged into power cable

Tom's Hardware: Over 1.4 million members in 6 different countries available to answer all your high-tech questions. Sign up now! Its free!

Ask the community Add a reply

Bottom Search this thread

Hello everyone,

So I am in in the process of building a new PC, and i am experiencing a strange problem. When I plug the PSU into the power cable, it automatically turns on without my pushing the power button on the front of the computer. I have the appropriate cable connected to the motherboard, so the power-switch on the front does work. It's strange enough that it happens, but whats stranger is the system actually POSTS, and I can access the BIOS and everything.

Any ideas why the PSU automatically turns on?

Add a reply

Does the power switch on the front also turn the computer OFF?
You might have the case power cable hooked up wrong - even if its in the right motherboard pin-out.

Reply to WR2

No, the power button on the front doesn't turn it off.

The power cable hooked up wrong? you mean the 20 pin (and the additonal 4 pin cable?) I mean, there is only one way to hook it up....

Thanks for your help btw.

Message quoted 1 times

Reply to Anonymous

option in bios for when the system returns from power loss...
it could be set up to turn on,
options are usualy: Off, Last State, On

------------------------------ Invented a new file compression... remove all the '0'. They are nothing anyways...
Q6600 O/C to 3.6Ghz wc
http://valid.x86-secret.com/show_oc.php?id=229261
Reply to MadHacker

that sounds like it makes sense, thanks, I'll try it!

Reply to Anonymous

Typically a BIOS setting would cause this behavior:
if the system is set to power loss setting: ON. I have my system on this setting. It will turn on as soon as I flick the powersupply switch on. NB when I shut the system down from the OS it will stay shutdown. I need to press the front panel switch to start it again.
if the system starts at odd times without the power switch it is probably a "wake on LAN" setting which is causing the system to wake up.

The front panel power switch pulls one of the 20/24-pin MB ATX header lines to a low state momentarily. It is very unlikely to be the cause of the problem. When they break you just tend not to be able to switch the system on any more!!

Bob

Reply to bobwya

Anonymous wrote :

No, the power button on the front doesn't turn it off.

BTW does the front panel power switch shut or reboot the system down if held in for 4 seconds?? I think mine boots straightaway after holding it in (because it is set to always be powered ON).

Bob

Reply to bobwya

BY THE WAY PLEASE HELP GUYS!! i have the same problem.

when i turn on the switch of the power, my pc turns on immediately ( light open) then i have to press the power button to switch and boot up. I dont know y my PC's PowerSupply turns on as soon as i turn the power switch! And when i turn off the machine, you can hear the PC turned off as the fan stops however the power supply is still on because you can hear it and the light is on. ANY IDEA GUYS????

Reply to Anonymous

@ OP, Try plugging the PSU in. Computer starts. Now shut it down. Now remove the cord. Plug it in again and see what happens.

guys im having a sort of same problem might be easier might be harder for you...i really would like a respond. Literally as soon as i plug in the power cord into the outlet in the wall; the pc will turn on by itself and nothing will work. nothing will show up one the monitor. nothing will work. is it the motherboard or the case or graphics card. i havent put anything new in it..what is wrong?!?

Message quoted 1 times

Reply to iamscarier08

iamscarier08

It is the motherboard that detects whether to drop the voltage on a signal wire to PSU to tell it to turn on. Have you got a really cheap PC case?? If so the on/off switch could be "bouncing" (where the 2 contacts bounce off every so often - with out operator intervention)... My flatmates PC did this recently - I thought it was my biaaatching overclock that caused it!! :sol:

Can you turn the PC off by holding in the power button for 4 seconds? Does it turn on again itself if you do this?

Bob

Reply to bobwya

I have a similar situation with a used pc that I bought recently
It's plugged into a power strip that has a switch on it
As soon as I turn on the power strip the computer turns on and boot's up normally after I shut it down with the software it stays off and I have to use the power button on the pc to turn it on but if I turn off the power strip and turn it on again then the pc will turn on again without me pressing the power switch on the pc
I pulled the small connectors from the motherboard that go to the power and reset switches and it still turns on when I turn on the power strip

So there is still something on the motherboard that is telling the power supply to turn on I just can't figure out what it is
The power loss setting is set to off in bios so I am not sure what else to look for
Could it be that power supply is sensing the initial power surge when it's first turned on and is somehow fooling itself to turn on ?
I don't know I am running out of rational ideas and starting to look for more strange things
The power supply is 130w that is used on a p4mdpt motherboard running at 2.4ghz
Any new ideas will be very much appreciated

Reply to status1

Ok I figured it out myself
It turned out to be the wireless pci card
After I pulled the card the pc no longer turns on when I turn on the power strip
Maybe it can be disabled by software I don't know I haven't looked into it that far
For now I am glad I was able to fix this mystery

Reply to status1

I have similar problems with my PC. when I plug the outlet into the computer, the computer suddenly turns itself on where the cpu fan and the power supply fan is on. however there's no start up nor any indication of any cpu activity. in the front of my computer, the light to the power indicator is on and the cpu light appears to be solid amber light. please help me you guys, thank you!

Reply to supergok2u4

You have a CPU light ?
That's unusual I think. Most pc's have a power and hard drive light I haven't seen a pc with a CPU light before
If that's the case than a amber light showing is not good for the CPU I would say either the cpu or the motherboard has some serious issues. Could be a short somewhere which would explain why the power supply turns on when you plug it into the outlet

Reply to status1

The motherboard LED that you are talking about is powered by the "always on" Standby Power Supply that every PSU contains. There is nothing wrong with either your motherboards or CPU's.

As long as the PSU is plugged into the wall and the power switch on the back of the PSU is turned on, that LED will illuminate. It does not mean that you have operating power going to the computer.

Reply to jsc

Dear Friends

I am also facing the same problem for last one month. I am using Compaq Presario V 3000 notebook since one year. When I pluged power adapter into electric pin my system is starting automatically. If i shut down my system with power supply, then the system automatically starting again. I have tried by recovering all softwares by using recovery tool. I have seen LAN setting also. It is not in Wake up mode. I have tried to go BIOs by pressing F2, Del, Esc, F8, F9< F10 and F11; but system not leading to BIOS. If anybody know why is happening or solution ple.zzzz share . Thank you in advance

Reply to gkcharan

Kind of a funny request but I actually need this feature.. I have a keychain remote that when the button is pressed it turns the adapter on..
So I want my pc to automatically turn on when I press the button on the remote, which then would supply power to the pc. What do I need to do?

Reply to unbreakable87

Those of you with pc's starting up unexpectedly:

1. Check your power management settings in BIOS.
2. Check your power management settings in Windows.
3. Does your keyboard have a power management key that may have accidently been pushed?

Those would be the three most common solutions. We just had a thread the other day and it turned out a user's friend accidently pushed the power management key on the user's keyboard. Another user accidently changed Windows power management settings.

Reply to JohnnyLucky

iamscarier08 wrote :

I'm having the same problem as this. Did you every figure out how to fix it?

Reply to lzacharyjw

i had this problem and fixed it with a new psu - it lasted 4 hours then back to the start, motherboard was goosed!

Reply to dejay2k9

Ask the community Add a reply

Tom's Hardware > Forum > CPU & Components > Power Supplies, PC Cases & Case Mods > PSU turns on when plugged into power cable

Go to:

Help |
Forum rules

There are 1227 identified and unidentified users. To see the list of identified users, Click here.

Page generated in 0.494 seconds

Focus On

PSU turns on when plugged into power cable

Forum CPU & Components : Power Supplies, PC Cases & Case Mods - PSU turns on when plugged into power cable