Total failure - short circuit or fried motherboard?

I came home from work to-day to find that my main computer had frozen (black screen, USB mouse light unilluminated, no response from numlock light, etc.). Pressing the "reset" button purported to reset it (drives flushed, etc.), but did not make the computer responsive (no POST beep; the speech error reporting stated "system failed CPU test"). Power cycling had no better effect. Having had this problem once before, and, after having removed all of the expansion cards, solved it by unplugging and later reconnecting the network cable, I did so, but this time to no avail.

Like last time I had this problem, I found that, when I looked inside the computer case, the little green LED that shines when the motherboard is recieving power from the PSU (i.e., when the PSU switch is on) turned off instantly when I turned off the PSU switch, unlike after several seconds while the capacitors discharge as it usually does. This is the exact same symptom as I had before, and, last time, removing the network cable reversed this trend (the light would stay on for a few seconds and then turn off with a little "eeep" sound), and, thereafter, the computer worked.

This time, however, removing the network cable had no effect, nor did removing all of the external cables apart from power, all of the internal expansion cards, the RAM, all cables connected to the motherboard other than the ATX power cable, and, eventually, the CPU. I have looked, and I cannot see any stray objects on the motherboard that might be causing a short circuit. I have blown off as much dust as I can, all to no avail.

I really have no idea what is causing this odd and very disturbing behaviour: I should be extremely grateful for any assistance. My system specifications are:

Asus P4C800E-Deluxe
P4 Northwood [email protected] (250Mhz FSB)
2x OCZ PC3700 Gold RAM (dual-channel, 1:1 FSB, actively cooled)
NVidia GeForce 6800 AGP
2x SATA HDD, 2x PATA CD/DVD devices
Windows XP Pro
Sound card
Digital TV card
Internet connected through external router

do u have the system on a battery backup or surge protector, if not maybe your outlet u have the compter pluged in overvolts sometimes and frys everything? or maybe your power supply is frying everything? do u smell burn electronics stuff?

my p4p-800D does that on rare occasion.
ive found 3 things i try, and usually one works, and im off and running again without that problem for another few months.
1. unplug it, let it sit.
2. power cycle it like a fool, using the ATX power button, and/or the PSU.(involves risk of true failure)
3. reset the bios jumper/reflash/new bios chip.
ive completely fired my bios like 3 times and ive found it acts like a fuse for the rest of the system - better to replace a $30 chip than a new mobo IMHO.

wrangler88 said:

do u have the system on a battery backup or surge protector, if not maybe your outlet u have the compter pluged in overvolts sometimes and frys everything? or maybe your power supply is frying everything? do u smell burn electronics stuff?

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Yes, it has a surge protector.

orionlion82 said:

my p4p-800D does that on rare occasion.
ive found 3 things i try, and usually one works, and im off and running again without that problem for another few months.
1. unplug it, let it sit.
2. power cycle it like a fool, using the ATX power button, and/or the PSU.(involves risk of true failure)
3. reset the bios jumper/reflash/new bios chip.
ive completely fired my bios like 3 times and ive found it acts like a fuse for the rest of the system - better to replace a $30 chip than a new mobo IMHO.

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I have had problems with that computer doing something very similar, but not the same, before, when it would fail to start up and give the "system failed CPU test" error repeatedly; power cycling would fix that. However, when I had the version of the problem that power cycling would fix, it did not have the issue with the green power LED on the motherboard. Last time that I had that issue (that time corrected by disconnecting the network cable), it was not fixed by power cycling. Did the problem that you have involve the power LED behaving in the way that I have described? And where can one get BIOS chips, anyway?

biosman.com is the vendor i use for bios chips. try that before junking the board.
no LED usually means dead board, and not dead CPU.

have you tried the old school trick where you have the PSU on, but the system off and you hit both the power and reset switches, then release the reset switch? i think its called the atx-power-good trick. i forget where i saw it.

and finally, what about SNDS/GNDS? could that be part of the equation?

orionlion82 said:

biosman.com is the vendor i use for bios chips. try that before junking the board.

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I shall bear that in mind, but I hope for it to be a last resort! Does it sell to the UK?

no LED usually means dead board, and not dead CPU.

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It's not that there's no LED: as I wrote above, it goes on when I turn the PSU on, but it goes off instantly when I turn the PSU off, instead of a few seconds later, as it should do (while the capacitors discharge). This sort of suggests to me a short circuit somewhere, but I'm not sure.

have you tried the old school trick where you have the PSU on, but the system off and you hit both the power and reset switches, then release the reset switch? i think its called the atx-power-good trick. i forget where i saw it.

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I haven't tried that because I haven't heard of it. What exactly does it do? Can it be done even when the CPU is not inserted?

and finally, what about SNDS/GNDS? could that be part of the equation?

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I had thought that it might be that until I removed the CPU and, as I wrote in my first post, found that the LED problem was still exactly the same.

I had a problem with my dads non-e board not booting. I had no idea what it could be. It turned out it was the bios not giving enough voltage to the ram to even start up. Who would have thought of that? After about 10 power cycles I finally got into the bios and upped the voltage and it came right up

If you take everything out and test the board by itself and not get any beep codes then the board is probably shot. I tried just CPU and video card without the ram, I got beep codes. When I tried it with the ram I got nothing. *shrugs* Good luck!

JT

man, you sound frustrated. i can understand.
biosman is not the only vendor out there, i would bet you can find one that does buisness in the UK. a quick google for you: http://www.google.com/search?q=bios...ient=firefox-a&rls=org.mozilla:en-US:official
the atx-power-good trick was to solve some odd fidly problem, and as i recall it was one of old hardware-meets-new hardware. sudden failure might not fall in that catagory, but anything is worth a try, right?

im gonna toss some stuff out that may or may not help: (shots in the dark)
do all your caps look good? no physical damage? no overheating? all your standoffs tight? no strange issues with the ac line? is the ATX power switch, harness and connector completeing the circut and working properly without intermittent shorts or opens or whatnot? how is the PSU? have you tested the rails? might you have an odd fan or molex connector or whatnot shorting out/not fully tight? havnt nicked any wires?
you might be onto something with the idea of a short, but allso i wonder how many components there are that can/do fail into a short...

JTanczos said:

I had a problem with my dads non-e board not booting. I had no idea what it could be. It turned out it was the bios not giving enough voltage to the ram to even start up. Who would have thought of that? After about 10 power cycles I finally got into the bios and upped the voltage and it came right up

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My problem is almost certainly not that, because of the LED issue described above.

If you take everything out and test the board by itself and not get any beep codes then the board is probably shot.

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That board doesn't do beep codes: it has a voice reporter. That was still working, as described above, giving the "system failed CPU test" message.

orionlion82 said:

man, you sound frustrated. i can understand.

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I am definitely frustrated. Thank you for persevering so in helping me

biosman is not the only vendor out there, i would bet you can find one that does buisness in the UK. a quick google for you: http://www.google.com/search?q=bios...ient=firefox-a&rls=org.mozilla:en-US:official

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Thank you. As I said, I hope not to have to get that far!

the atx-power-good trick was to solve some odd fidly problem, and as i recall it was one of old hardware-meets-new hardware. sudden failure might not fall in that catagory, but anything is worth a try, right?

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Possibly, although I don't quite see at the moment how it could solve the LED issue, which seems to be an indicator of the underlying problem.

im gonna toss some stuff out that may or may not help: (shots in the dark)
do all your caps look good?

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As far as I can see: I did look at the capacitors, and couldn't see any problem.

no physical damage?

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I can't see or smell any.

no overheating?

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That's hard to tell, since the system has had time to cool. There are no burn marks that I can see, though, nor any burning odours; however, the system would have been sitting there for many hours with fans full on after it failed, in all probability, since I was out at work, so burning odours may long since have dissipated by the time that I came home.

all your standoffs tight?

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Stand-offs are the things that connect the bottom of the motherboard to the case, yes? They all look all right, but it's sort of awkward to tell. I was looking for anything connecting one of the little metal dimples connected to some or other component underneath the motherboard to the case that might be the cause of the shorting, but couldn't find anything.

no strange issues with the ac line?

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If by that you mean the mains, there are no other problems with electrical equipment in the house, including electrical equipment plugged into the same outlet as the computer, such as the ADSL router that I'm using to send this message now.

is the ATX power switch, harness and connector completeing the circut and working properly without intermittent shorts or opens or whatnot?

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I have disconnected all of the switches and LEDS from the motherboard to eliminate this problem, and I still get the motherboard LED problem described above.

how is the PSU? have you tested the rails?

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No, but I don't really know how to without using software on the computer on which the PSU is installed. I suspect that one needs equipment that I don't have...

might you have an odd fan or molex connector or whatnot shorting out/not fully tight? havnt nicked any wires?

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I have disconnected every fan that plugs into the motherboard: I still get the LED problem.

you might be onto something with the idea of a short, but allso i wonder how many components there are that can/do fail into a short...

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I suspect very many... does the fact that I had the problem before, but solved it by disconnecting and reconnecting the network cable (after power-cycling the network switch), tell you anything useful about this problem now?

I am just about to go away for the week-end on a course, so I shan't be able to reply to messages until Sunday evening. I should be extremely grateful if people could post as many ideas as they can think of, and I can try to investigate them all (and reply) when I get back.

Thank you all very much for your help so far!

I am back from the course now...

Update: when I listen to the voice-POST now, it tells me, at first, "no CPU installed", then "system failed CPU test; no CPU installed" after about 5-10 seconds. Before I removed the CPU, it would just say "system failed CPU test" after 5-10 seconds, and was silent at first.

Does that help to narrow down the problem?

Edit: I tried the power-good thing: no difference.

Hmmm, See if you can get your hands on another cpu. I'd take the motherboard out of the case and only connect the bare essentials, vid card/keyboard and cpu fan. Then go from there.

If it's not seeing the CPU I'd place blame on either the board/cpu but there's no way of really telling without testing.

Sorry to hear about your problem and I hope you get it figured out. I've had my p4c800-e deluxe and p4 3.0C for quite a long time with no issues.

The heatsink may have gotten loose. The above symptom sounds like what can occur when the processor got fried, because of the heatsink popping off.

RJARRRPCGP said:

The heatsink may have gotten loose. The above symptom sounds like what can occur when the processor got fried, because of the heatsink popping off.

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yeah, but thats prety hard to do with a pentium 4. not impossible, but there are a few safeguards in place.
1. they throttle
2. they shut down -
when there is an overheat condition.

maybe if a machine is overclocked, under a heavy load (prime, folding) in might not shut down soon enough if the HS/F is removed.

ive actually tried it once with my current rig under the above conditions. yes, it throttles, yes it shuts down, but it beeps, and you get warnings and whatnot. a few boot cycles and all was right with the world again.

$30 for a bios chip is still cheaper than a new Proc - but you gotta rule out the other hardware first.

oh, and as a general rule, the asus voice thing is not really to be relied upon.
granted this might prove to be the one time ive encountered where its right, but ive had all kinds of strange things Miss Asus has jabbered at me repeatedly in broken english in a low-fi style that were in fact, wrong.
i just consider it an arbitrary "something is wrong" message, and i dont find it particularly accurate. who knows though....

RJARRRPCGP said:

The heatsink may have gotten loose. The above symptom sounds like what can occur when the processor got fried, because of the heatsink popping off.

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I can't see how that can be the cause of the problem when the LED issue that I have described is constant even when the CPU is removed.