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My computer is broken

Discussion in 'General Hardware' started by myriad, 14 Aug 2006.

  1. myriad

    Gangster

    Joined: 17 Nov 2003

    Posts: 270

    I am fairly decent at diagnosing and solving most computer problems but my main machine is totally owning me at the moment.

    Specs:

    Asus A8N SLI Deluxe
    2GB OCZ Platinum RAM
    7800 GTX
    500W Seasonic PSU

    My problems are so weird and varied I'm getting a bit lost:

    First problem that showed up a few months ago is that computer loads ok, gets to windows logon screen and then turns itself off. After messing around for quite some time I find that removing the network cable(!) allows the computer to boot. So I disable the on board LAN port and enable the secondary on board lan port. Computer works.

    Same problem crops up, solvable with a remove and swap of the network cable.

    A new problem, computer won't boot, press the power button and nothing happens. Look inside the case and find that the motherboard power LED is flashing, as far as I can tell this means nothing offical, ie it is not a signal. So I unplug the power and leave the pc for a while, plug back in and it works.

    Same problem crops up a few times, solvable by removing the power lead for a period of time.

    At this point I am considering a possible problem with either the psu or the motherboard, but since I do not have a spare psu that is 24 pin and I do not want to waste money I do nothing.

    Problem seems to get worse, it is now not possible to boot, led continues flashing. I manage to borrow a high powered psu, it is only 20 pin, but I have read that this is enough to power the mobo. I wire it up and it boots, pc blue screens on starting a game, but I sort of expected that since the mptherboard is not been fed its full power requirement.

    So I bite the bullet and buy a new psu (listed above). Computer still works, however a couple of crashes are later experienced.

    At this point I have a strong feeling that the motherboard is the culprit. This morning I try to turn the pc on and it boots, gets to windows and restarts, gets stuck at pre POST, no beeps, fans spun up to maximum. I remove a ram stick in desperation, try to boot, I get 1 long beep and 2 short, this indicates a VGA problem, I plug the RAM back in and the pc boots again, try safe mode, pc crashes just as login starts. I remove the other RAM stick, no boot, no beeps, I replace it, no boot, no beeps.

    This could go on and on, if I remove the power for a while and come back it may or may not boot, it then may or may not crash at windows logon.

    This is where I am, I am stuck because the symptoms I am seeing confuse me, in summary:

    Flashing power led, no boot and crashes could indicate psu or mobo, replacing psu has not solved either.

    Non boot, everything is powering up so this indicates mobo again.

    Crashes ALWAYs occur just after windows login, in the past removing the network cable allowed full boot. This is tricky, why would a hardware failure on a mobo cause crashes on windows logon? Why would removing a network cable allow a boot, why is it ittermittent?

    BIOS beeps indicating failed gfx card, the gfx card is fairly new, is the mobo just going crazy and reporting bad errors? If the card really has got a problem, why does it boot sometimes and not others? Maybe a gfx card problem could cause a crash on windows login, but I only got this error code for the first time when I removed a stick of memory, this points more towards a mobo error than gfx.

    What should my next move be? I have already spent £70-80 on a psu that has not solved my problem, money I don't have, what are the chances that replacing the mobo will still leave me with a bad system?
     
  2. Echo toxin

    Gangster

    Joined: 29 Jun 2006

    Posts: 470

    Location: Cheshire

    I would get the system right down to the minimum components needed - one HDD, one optical drive, 1/2 sticks of RAM, no expansion cards (except video), no network cable, etc.

    Then I would wipe the HDD and reinstall Windows from scratch and see what happens. If it's OK then start adding one component at a time and using Windows for a bit to see if anything happens after each addition.
     
  3. myriad

    Gangster

    Joined: 17 Nov 2003

    Posts: 270

    Thanks for the reply, I know this is standard procedure when there is a problem with a pc that is doing odd things, but my system is so bare I don't think it would be worth while. I have 1 hd, 1 optical drive, 1 floppy, 2 sticks of ram, 1 gfx card and 1 sound card. I just removed my sound card, the pc booted (but I had also left it unplugged) and froze half way into the windows boot process. Fair enough this could still point to the sound card, except that on restart the pc span the fans up and froze before POST, something that has nothing to do with the removed sound card or the Windows installation.