PC dead one day, then alive the next.

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Barrymore

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My wife's PC is giving me grey hairs.
One day it will boot up thru to Windows then another time nothing happens when switching on.
I have tried different PSU's with the same results.
The other day it did not switch on so I removed the front panel and fiddled with the cables to the power switch.
After doing this a couple of times the reboot button lit up then the bright power switch light came on indicating that the PC was booting up. It went thru to the desktop but after a few minutes it rebooted on its own. Later it again would not switch on. Pressing the power button repeatedly got the fans running at one stage which lasted for a couple of seconds.
I again removed the front panel and immediately the PC booted up. The switch is not faulty as I tried another from an old PC. Could the problem be a dry joint or bad connection, possibly in the vicinity of the front panel?
Any suggestions would be most welcome.
 
Disconnect the mains from the PSU & leave for 15mins, try again and see what happens.
 
Barrymore said:
My wife's PC is giving me grey hairs.
One day it will boot up thru to Windows then another time nothing happens when switching on.
I have tried different PSU's with the same results.
The other day it did not switch on so I removed the front panel and fiddled with the cables to the power switch.
After doing this a couple of times the reboot button lit up then the bright power switch light came on indicating that the PC was booting up. It went thru to the desktop but after a few minutes it rebooted on its own. Later it again would not switch on. Pressing the power button repeatedly got the fans running at one stage which lasted for a couple of seconds.
I again removed the front panel and immediately the PC booted up. The switch is not faulty as I tried another from an old PC. Could the problem be a dry joint or bad connection, possibly in the vicinity of the front panel?
Any suggestions would be most welcome.
Click to expand...

Power Supply and/or motherboard needs to be replaced.
 
Bap capacitors on the motherboard, specially on the power regulation side of the motherboard.
Look for bulging/vented capacitors, if you find some and is handy with a soldering iron you can replace them.

Had the same symptoms, was driving me nuts. Probably reinstalled windows a dozen times before I though about checking the capacitors.
 
Could be that something is shorting out somewhere or indication of a faulty power supply.
 
Your rebooting is most likely from Overvoltage or short-circuiting protection built into the motherboard.

The difference of one day to the next means that it's humidity and/or temperature related.

If you're living close to the coast or the pc is near to a humidifier or aircon with humidifier try move the pc to a drier, cooler area. That, or do fault-finding on your motherboard.

Otherwise, buy a new mobo.
 
I also think this would be related to your motherboard.

However I would like to know what happens when you take the front panel connectors off of the motherboard and then short the pins to start it up.

Even if it boots up fine, you would probably still need to get a new motherboard.

I would suggest taking it to a computer shop to test the components. They will then be able to confirm which component is the culprit.
 
Firstly, it is not the power supply. As previously stated, I have tried other PSU's that are perfect but the problem still exists.
Yesterday the PC was on all day until load shedding kicked in. This morning it would not switch on. I removed the front panel,
touched the wiring then it switched on but as soon as I started to clip the panel back into place it would switch off then on again once I
released the panel. Definitely a short at the front panel, possible the re-boot button is shorting causing this on and off behavior????
 
Hopefully you have a nice motherboard in which case you can remove the front panel connectors and use onboard buttons to switch it on and off?
 
Do you know how to short the pins on the motherboard to switch the pc on and off?

If you do you, try to short the pins to switch it on. If it works, it could be the switch that is stuck or faulty.
A safer option could be to swop the power with the reboot plug and try using the reboot switch as the power switch.
 
Hectic said:
Do you know how to short the pins on the motherboard to switch the pc on and off?

If you do you, try to short the pins to switch it on. If it works, it could be the switch that is stuck or faulty.
A safer option could be to swop the power with the reboot plug and try using the reboot switch as the power switch.
Click to expand...

I have checked the voltage on the board's front panel pins - 3.3v on the reboot pins and power switch pins.
I think I previously stated that I had tried another switch but the problem remained.
 
Barrymore said:
I have checked the voltage on the board's front panel pins - 3.3v on the reboot pins and power switch pins.
I think I previously stated that I had tried another switch but the problem remained.
Click to expand...
Apologies, I missed that part it seems.
 
Do you have any flash drives/ usb storage devices that you leave in the the pc when switching it of or on?
My previous pc had the same issues, did not want to switch on and when its on it does not want to switch off it just hangs in the shutting down screen, after pulling my portable HDD out it goes off...
 
I doubt it's a bad cap if it works some of the time. Not impossible; just not the most likely cause, if you ask me. Most likely causes, if not the PSU (EDIT: see below):

1. External HDD or flash disk plugged in and the BIOS is configured to boot from external disks first (solution: remove external disks or reconfigure your BIOS)
2. Bad contacts on PCI card (solution: ensure all PCI cards are seated firmly and perpendicularly)

I actually struggled with #2 for hours due to a schizophrenic BIOS (ASUS board). My graphics card sagged once and I thought putting it in properly would fix things, but little did I know the BIOS decided to alternate between the discrete graphics card and on-board graphics after the first time it didn't detect anything in the PCI slots. The PC was booting fine every time; the video just sometimes came out on the on-board DVI/HDMI instead of on the graphics card outputs, despite the BIOS being configured to prefer the PCI card. I fixed this (weirdly) by removing the backup battery for a few minutes before booting again. I guess this forced the BIOS to restore its default settings correctly.

EDIT: sorry, only read the last part OP's post now. Maybe the power button itself is faulty? I once had a case where the power button sometimes got stuck in the "down" position.
 
Last edited:
Had a pc with bad caps . Did not want to switch on . Had to heat up the motherboard with a hair dryer . Replaced capes worked fine after
 
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