PC turning itself off

[Deluks]

I am having the same problem as this guy.

I remember fixing a friends PC last year with a 'fluffy' CPU cooler, but mines ok in that respect, it's a Zalman and is securely fitted, fans spinning ok.


I get no beep with mine, it just shuts off like someone's pulled the plug. Then it won't turn on again without cycling the on/off switch on the PSU (Enermax noisetaker) This takes a few 'goes' to 'latch' and start booting again. Usually happens about 3-4 minutes after turning on, then more frequently after that. Some times it comes on for a few seconds before shutting down.

After several of these 'false starts' the machine boots up fine and runs all day long with no probs. It's like an old car on a cold day, a bugger to get started, then ok after that.

I'm thinking it must be psu problem or motherboard/switching problem.

How should I best be troubleshooting these?

Possibilities could be overheating/loose component/grounding issue but none of these tally with the fact that it only happens when the PC has been off for a while. It makes no sense at all???


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'May' be related but my VGA card (radeon 9800pro) died on me a few weeks back. The system was running with no apps or windows open, I was out the room a few hours, when I came back the machine was off and wouldn't reboot til I swapped out the card. Tested the 9800 in 2 other machines (pals) and again no boot so that's a goner.

 

[Igorian]

Without seeing it, it's one of those "cannot be sure". The PSU may be faulty or it could be shutting down to protect itself.

Watch for it shutting down and then, once off, press and hold the power button for approx 10 seconds (manual reset). Now try and start it. If it comes on straight away after a manual reset, then it's a reasonable indication that either the PSU is on it's way out, or something is causing it to short/overload.

The 9800 boards are quite power hungry and some PSU's don't deliver what they promise. When they are 'overdriven' for a period of time it can cause the electrolytics to dry out prematurely, causing this type of problem. In my experience, people don't pay much for the PSU because they don't offer any 'real' benefit. However, it should be considered one of, if not the most, important component. I always liken a cheap PSU to filling a Porsche with 2 star fuel.

 

[Deluks]

Thanks for the reply, some useful info there.

The 9800 boards are quite power hungry and some PSU's don't deliver what they promise. When they are 'overdriven' for a period of time it can cause the electrolytics to dry out prematurely, causing this type of problem.

That's interesting, another problem with troubleshooting this machine is that it's had so many upgrades in the last few months. Mobo and CPU (from amd2800xp to a 3.4 Prescott), then another hard drive was added to make 3, although after a while I removed 1 so I'm down to 2 now. Then swapped out the ram for 2gb of faster. Lots going on inside my case!

I know the prescott's are quite power hungry so maybe I've 'overdriven' the PSU?

I always thought enermax were a decent brand, any experience? This one cost about £75 and is less than 3 years old. It even says 'Prescott ready' on the box.

Manual reset. Do you mean the case button or on the psu itself?



Funny, it's been up n running for 18 minutes today and hasn't shutdown yet.

 

[Igorian]

Like I say, it's difficult to diagnose without seeing it. The PSU you have is from a good manufacturer, but you don't mention it's spec. It's best to get one with fully independent modular supply rails (IMHO).

Yes, I mean the power button on the case. Pressng and holding for 10 seconds will reset it.

To diagnose the problem, you may have to resort to a basic build and add in the extras one at a time. Failing hard drives are also a common cause of excess drain, in my experience.

 

[gcol]

Don't rule out the Zalman heatsink. I had one a while back and had trouble with it - I think it was distorting the motherboard and causing all sorts of hassle.

 

[Deluks]

Funny, hasn't happened the last couple of days. Got a new vga card installed yesterday but I don't see how that could've made a difference.

I tried the manual reset thing, 10 second hold while the pc was off.

What does it do exactly? Maybe that's cured it?

The psu is enermax noisetaker 470w, atx v2.0 with 'sfma'?


I found a review of a 600w version of this PSU and there was some interesting points raised (halfway down the page)

 

[Doc Lenny]

May be related but my VGA card (radeon 9800pro) died on me a few weeks back.

Funny, hasn't happened the last couple of days. Got a new vga card installed yesterday but I don't see how that could've made a difference.

Hmmm, sorted now?

 

[Deluks]

May be related but my VGA card (radeon 9800pro) died on me a few weeks back.

Funny, hasn't happened the last couple of days. Got a new vga card installed yesterday but I don't see how that could've made a difference.

Hmmm, sorted now?

Well Wednesday and Thursday it didn't happen, despite it happening every time I booted for the last couple of weeks.

The vga card went in yesterday afternoon. After 2 successful startups.