PC spontaniously turns off w/ blinking power light

[techleet]

Hey fellas. ltns. I have a big problemo.

My home pc recently started spontaniously shutting off. Not a full shutdown, it just shuts off! One second you're surfing the web, the next second it's like the electricity went out! When it shuts off, the power LED on the case blinks.



I figure it's the power supply or the motherboard, but I wanted to get a second opinion before I cough up the $.

Ideas? Thanks!

Windows XP Pro
Anatec full tower
Asus A7V mb
Athlon Thunderbird 1200mhz
386mb pc133
soundblaster live! value

[TripleRLtd]

All quality parts, so one step at a time.
It could just as well be....well almost anything at this point.
Start here:
http://forums.windrivers.com/showthread.php?t=53525
Then do the basic steps in diagnosing problems:
Remove everything but the VGA temporarily.
Do you use a modem or is it broadband?

[techleet]

Going step-by-step systematically removing cards is usually a great idea, but this problem is intermittent. As far as I know, the only thing that will make a machine spontaniously shut off is a bad motherboard or power supply.

What i'm asking is, "which one?"

[DocPC]

Going step-by-step systematically removing cards is usually a great idea, but this problem is intermittent. As far as I know, the only thing that will make a machine spontaniously shut off is a bad motherboard or power supply.

What i'm asking is, "which one?"

My first thought is PSU.....and it's cheaper.

[techleet]

Another odd thing happened at the same time this problem occurred: Suddenly my Soundblaster Live wasn't being detected by the bios. I moved the card to another slot and the bios found it again. I shouldn't have to do that though, because this machine has been running strong without any changes for a couple years!

Initially I thought it was the power supply, but after the soundblaster thing I was leaning towards the motherboard. BUT, could a bad power supply make one of your cards not work, simply because it doesn't have enough juice to power everything...?

[TripleRLtd]

As Doc says a PSU is cheaper, but that was before this last LARGE little detail.
When slots start not working, well.....
Did you know that Antec and Powmax make power supply testers?
I like the PowMax as it has more features.
Do you do any work on computers besides your own?
If so, its time to start carrying things like PSU's and testers.
If not, then its back to guessing for us.
As for me, I have seen software as well as other hardware cause reboots and shutdowns.
Hence, my step by step approach suggestion until you mentioned the soundcard problem.
Also, this is why I asked if you had a modem.
How intermittent, and is there anything exactlly the same when the problem appears, such as being on the Internet?

[techleet]

How intermittent, and is there anything exactlly the same when the problem appears, such as being on the Internet?

Thanks for you response.



The problem is 100% intermittent. The machine has been up for 10 minutes and then dies, or it could be up for an hour and then dies, both times when just at the login prompt. Other times I was surfing the web. Another time I was burning a cd.

I don't have a psu tester, and I don't want to buy one. I used to work in IT and might have needed one then, but now it's a little overkill.

As for the soundcard, yes it was a bummer but this soundcard has well documented issues with the Asus A7V and has done this serveral times over the past couple years, so I wasn't too concerned about it. What struck me as odd was the fact that I hadn't made any system changes in quite a while, but like I said, it's been known to happen.

I don't have a modem. Internet is through a 3c905b nic.

I can't see this being a software issue. I've heard of software shuttdown windows and/or rebooting your machine, but not forcing a total power failure.

[ilovetheusers]

Just guesses:

Reset the BIOS to defaults and see if it keeps happening.
If anything is overclocked, set it back to default.
Look for overheating issue as well, make sure the HSF fan is on properly.


Also, had exact same issue with one of my home PC's about a month ago. One of the RAM modules decided to stop working properly. Works perfectly in anything else I put it in and worked with this system for 2 years previously. One day it decided not to, no idea why. I decided not to work issue as I already have 512mb of ram in the system and needed this chip for another system anyway (so I'm not much help am i?).


Also - note I have seen sound cards not work when the slot is moved in many a board. I'm guessing the BIOS or the OS is holding onto an IRQ assignment for it and expects it to be in a particular location or something, something, something. Moving it back has worked fine for me in the past.

[TripleRLtd]

Hey ILTU:

(so I'm not much help am i?).

Yes you are indeed.
More things for him to try, since it isn't necessarily a bad MB or PSU.
Remember, I said isn't necessarily.

[Tekboy]

My experience is that software CAN shut you down, so I would not rule that out just yet. If your power indicator light is blinking after it shuts off, it sounds like something is possibly messing with the ACPI functions on your mainboard.

So, while it could be the hardware, I would NOT rule out software at this point. Does it happen in Safe Mode? What is the longest it will run before it shuts off?

Fascinating, Captain.

[jimmm33]

Look closely at the mobo. Is there any capacitors leaking or swollen?

I have seen boards do this and they often have bad caps.

[arch0nmyc0n]

In my experience Asus motherboards and Thunderbird chips have a tendancy to be fireballs of heat... have you checked the CPU temperature in the BIOS? if you haven't replaced the fan it's possible it's clogged or the fan is slowing down or something like that...
It might be overheating to the point where the mobo says "%#$% that, I'm shutting off before it kills me" and I've seen it happen where the heat damages the board where it is functional but has minor problems always...
If it is a heat problem, silver based heat grease (thermal compound) and a new heatsink fan may correct the problem...

That's my two cents worth

[Garak]

It could be faulty caps, I had a simular problem with a MS Intel 815E board, fired up 10-20mins later shut down or locked up. I would advise you look for buldged or leaking caps. Just to bam up Jimmm33's theory.