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  Power supply problems, computer won't turn on. 
 
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Luke Mertens Apr 23, 2003, 02:02pm EDT Reply - Quote - Report Abuse
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I have a 350 Antec power supply, and every once in a while my computer won't turn on when I hit the power button. I wiggle the cord around and unplug it and plug it back in and it still won't turn on. But I found that if I unplug the power cord and then plug in a different power cord to the power supply that it will turn on again. Also when I plug in the new cable I think I can here some static discharge or something. Could this be due to bad power from the wall or maybe a bad power supply?


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Ralph Bacon Apr 23, 2003, 02:36pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
That's not static you hear, that's mains sparks flying as you disconnect the power from the mains. Always switch off from the wall socket first!

You're probably aware that the on/off button on the front of the computer does not actually do anything other than signal the power supply unit to switch on or off. So if there's a problem with switching ON only (ie it will always switch off gracefully when you hit that button) then the problem is to do with your mobo/PSU.

When you unplug then you really are shutting things down properly. Many mobos are kept alive and running when connected to the mains unless the power is actually off at the socket. That's why you must always switch off properly before replacing PCI cards, processors etc!!

Try switching off at the wall socket regularly and see if it always come back on line when you then boot up...

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There are 10 types of people in the world; those that understand binary, and those that don't. Well I thought it was funny...
Bolda May 10, 2003, 02:10pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
this problem can also be caused by a power supply that has a weak standby current. the mains voltage may have dropped a bit due to high demand in the hood, and the standby current that was already weak drops to a level that the mother board cannot recognize. the standby current is always supplied to the mother board even when it is off, when you press the power button it lowers the voltage on the standby pin to ground signelling the power supplie to power up the main power. to many pci cards in a system that use the standby voltage eg. wake on lan nics and some video cards, ps2 mice and keyboards, can drop the voltage to much and stop a pc from powering down or up.
try and get a power supplie that has a larger standby current/

Ash Rocks Aug 06, 2003, 07:17am EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
I have this exact same problem, ever since I bought a new case with a new powersupply in it, I have to completely turn off the power and unplug the cord and re-plug in back in again before it will turn on. I had no problems at all with my old case and PSU, with the same mobo. My friend said the same problem happened to him, and he started using a different Power Cord to the PSU and it fixed the problem. I found a different cord, and the computer powered on and off twice perfectly before reverting back to its regular habbit. It may have been a co-incedece that at this time people were using less power in my area or something. There are two things I dont understand though, 1. Why is this happening when the PSU I have in my case is meant to be a top of the line model. and 2. Why would it somehow work for a bit by changing my cables? Arent all cabels the same?
Well thats my gabble, reply if you know a solution to my problem, besides buying a new PSU.

Bolda Aug 18, 2003, 10:40am EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
this is a strange problem. my mobo and psu combo have had the same problem from time to time. sometimes when i reboot, my mobo will not run the pre boot test (memory test) and just sits there waiting. if i press the power button off then back on it is ok. tests mem and then detects ide drives. and boots. I have found that if i remove my usb cable modem and/or usb keyboard/mouse combo then this problem will never happen. i think that it has to do with the small standby current supplied by my psu. the serial ports use it, usb, video, ethernet (wake on lan). when i have all of these things configured to wake the pc from a power down state, this problem can sometimes happen. but i am a least getting power to the mobo. video bios boots and then it hangs at the mem test.
sometimes if i disconnect the power cord from the back of pc, and put it back then boot, my cpu speed resets to the default speed of 500mHz, and i have to enter bios and then exit again to reenable 1gHz.
this leads me to think that by disconecting the power cord that some static carge that has built up in the case may reset the bois.
this same thing could be happening to you. you may have a bad earth connection in your house. the earth rod (mettal rod that is driven into the ground outside your house and connected to the earth circuit of the dommestic wiring of your house) may be in very dry ground. it needs some moisture to for a good circuit with the earth. ans so your psu may be building static that is inhiditing the on/of circuit from working. when you press the button on the case the standby voltage is connected to the earth circuit dropping it to 0volt, this signals the psu to power up. if the ground circuit is not working correctly then any static in the case can prevent the on/off circuit from dropping to 0V. disconnecting the power cord must discharge any static. tyr connecting a wire from a screw on the outside of the case to the plumbing (cold water pipes) and see if this helps. if it does then you may have to get an electrision to fix the earthing problem in your residence.

Eva Sutorowski May 21, 2005, 12:50am EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
Hi everyone
Just the other day we had a storm, lights still stayed on but all things plugged on the power points turned off, so the wires tripped. After turning the safety switch all was fine except the computer tower won't turn on. Should I change the power supply first or has anyone else got a different opinion. Please get back to me that would be much appreciated. thanks.

Adam Long Jun 09, 2005, 03:06am EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
I have a problem which sounds similar to what many of you describe. At first, I could just turn off the pc and then turn it on again and everything would boot normally. As time goes on, it has become more and more work to get my machine to post.

Tired of the problem, I slapped a troubleshooting card into a pci slot and discovered that the 3volt standby power led was not showing any power. After a couple of resets, I start to see a light pulsing which then builds to solid green over the course of a few minutes. When the led is fully lit, I can turn off the computer, turn it on again, and watch it boot.

My inclination, at this point, is to suspect the power supply. I'm also inclined to believe that some, or all, of you are assuming your machine started after changing the power cord. I can see no logic at all in this line of thought, and my little LED tells me otherwise.

Anybody?

mike britt Dec 12, 2005, 07:51pm EST Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
ok what about this...

naked setup, (psu, mobo, video)

the fan spins and then everything shuts off... except an LED on the mobo
shut of switch on psu and the LED goes off.
few seconds later, flip switch and the fan spins for 2x longer... everything goes off except LED
shut of switch on psu and the LED goes off.
few seconds later, flip switch and the fan spins for 2x longer... everything goes off except LED
shut of switch on psu and the LED goes off.
few seconds later, flip switch and the fan spins for 2x longer... everything goes off except LED
shut of switch on psu and the LED goes off.
few seconds later, flip switch and the fan spins for 2x longer... everything goes off except LED

after twenty minutes of this the motherboard will finally STAY ON

so then i plug back in the hard drive and it's ready to go

-----------

what is this all about? when the problem first happened it took ten minutes the next day it took half an hour now it takes me about an hour to boot up. - now i just flip the "on" switch and leave it alone for an hour then it's ok... do older computers need time to "recharge" or something?


Steffen Lewenhardt Jun 09, 2006, 06:14am EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
Mike this is -exactly- the same problem I have! Could anyone shed more light on this?

Usually over night I disconnect the entire PC & monitor from the power supply. I have found that when I just keep everything connected over night, bootup attempts reduce to 1 to 3 "bootup-please-button-pushes" in the morning, then everything works fine.
If I instead disconnect everything as usual, it now takes me up to 20 minutes of repeatedly begging it to boot up completely. This increased over the course of a couple of months.
I have also found that switching the power supply on the back of the case on and off in between try´s seems to reduce the number of attempts a bit.

Any idea´s ?

jose silva Jun 23, 2006, 04:31pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
my problemis diferent nothing turn on ,and i even tried a different power supply. i need help. thank you

Klay Abele Aug 02, 2006, 01:55pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
Hey, I recently came back from a trip and when i went to start my computer up (which the power strip it was on was off.) the button did not work. I took off the side panel to see if my mother board was getting power. The LED on the mobo was on, i reconnected the "power sw" cord, but no result.

any idea's?

-Klay Abele

Meats_Of_Evil Aug 02, 2006, 02:15pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
Try using another cord. It may seem stupid but it happened to me once and If I would've know early I could have saved 300$ from worthless hardware swaping.

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Everything I write is Sarcasm.
Klay Abele Aug 02, 2006, 03:25pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
Hey, I tried swapping power cords, Still having the same problem. I dont think its my power supply thats the problem.

Brendon Fredlund Aug 16, 2006, 04:37pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
I also went on a trip and when I returned, my computer would not turn on! Our house sitter said the PC wouldn't turn on for her either, though. There are no noises or anything when I press the power button, just silence. I am going to take a multimeter home with me from work and test the power switch and the MOBO test points. After that, I'll use another PS to see if that is the problem. The strange thing is that a green power light comes on the MOBO when I plug the PC in, but the power button does nothing. It is like the power button just doesn't work or something. I'll keep you guys posted.

Klay Abele Aug 17, 2006, 04:09pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
Hey, i found out wat the code on my MOBO meant, it read " F.3. " and when i looked it up it said 'Power Supply Sequence Error' so i'm pretty sure I have to RMA my power supply.

Brendon Fredlund Aug 27, 2006, 12:43pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
I changed the PSU and everything works fine. If you are still having problems, get a larger PSU and see if that fixes the problem. It seems like the most common problem.

Randy Tejada Sep 29, 2006, 11:26am EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
I came back from a trip and one of my computers wont turn on. They we're both turned off before i left. I tried several time to turn in on but nothing. No fans, sound anything except the little green light on the Motheboard. I unplugged and re-plugged the power supply and i heard something like small little spark noises. I smelled the unit around the fan area and it smelled a little burned. So i went ahead a bought a new Power Supply thinking it would solve the problem. When i installed it nothing would turn on, just the little green light?
Anyone have any ideas?

Art Bianconi Mar 09, 2008, 12:19pm EDT Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
This problem has happened a lot with all my electronic devices including my TIVO, my television sets and monitors. In the final analysis, the problems were all caused by a build up of dust and carbon soot caused by a malfunctioning oil fired furnace.

It was compounded by a poorly fitted flu pipe to the chimney stack and by leaks around the combustion chamber. The last two problems were created by the furnace repairman!

In every instance, the problem was solved by removing access covers and using compressed air to purge the accumulated soot from within the device.

Soot is carbon in fine particulate form. That's the same material used to make resistors. As the accumulated soot builds up between live circuits, it eventually forms a low resistance short. Now a direct short that causes burned circuits, but rather a resistive short that drains needed voltage from a circuit either to ground or to an adjacent circuit on the board. The low voltage circuits common to today's electronic devices, do not have surplus voltage to tolerate this condition and while the short does not normally damage anything as in high amperage short circuits, it does drop the voltage across sensitive circuits to a value where the machine ceases to function.

Another trick is to merely pop the small BIOS battery, that disk type, nickle sized one on the motherboard and let the PC simply sit there for a few minutes.

I am not sure why removing and reinstalling that battery should make a difference but it often does.


Donnie Tittle Apr 21, 2008, 07:48pm EDT Reply - Quote - Report Abuse
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>> Re: PC wont turn on but has Power
I have a issue i am looking for more input on i built a PC around a Year ago and all was good for about 4 months then i had trouble with my mouse and my Kayboard going out i would then hit the reset switch and reboot my PC with everything working fine THEN one day my mouse and kayboard went out so i hit the reset switch as normal and nothing happend no boot screen nothing so i thought it might be my mobo so i got a newone (exact same Mobo) and replaced it and same thing all lights are on all fans kick on CDROM powers up Hard drive seems to be powered there is nothing wrong with my video card yet i get nothing on the screen NO boot screen bios post screen NOTHING if anyone has any ideas i have allmost replaced the whole PC minus the HD and tower is it possible this is a Power (or lack there of) issue ????

Fletcher Garrison Dec 29, 2008, 04:17pm EST Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
Looks like you got yourself a fried cpu buddy. Whatever problem you had before doesn't matter at the moment you got to replace the cpu.

Tommy Breen Feb 18, 2009, 03:17pm EST Reply - Quote - Report Abuse
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>> Re: Power supply problems, computer won't turn on.
the computer in my room has not worked for around half a year to a year. i think it is because when it was working i never turned it off, not once, so it ran months on end without being shut off for a second. up until now i have learned to live with it, but i couldnt take it anymore, so i tried plugging it into a diferent socket, then i switched the power supply. after that all that happened was the cooling fan turned on and stayed on. PLEASE HELP!!!


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