Computer Shuts Down after Half a Second

Hi All,

I built a pc several years ago. It's run without problems until now. When I press the power button to start it, it powers up for half a second, then shuts down completely.

Every fan starts up during that half second the power is on. I've tried unplugging the dvd player, the hard drive, the motherboard, and I've pulled the RAM. I also pulled the battery for ten minutes and shorted the prongs by the battery before putting the battery back. In all cases the problem remains. I did just notice a small amount of brown crud on top of one of the mobo's capacitors which I then carefully scraped away. The capacitor looks undamaged but that obviously isn't a good sign. The only unusual thing that happened leading up to this in the last several days was the computer, twice, without warning, shut down after it had been on for several hours. It simply flashed the standard XP warning, "Windows is shutting down now," and shut down. The two times after that happened, when I restarted the computer, it started up with no difficulty or any indication once it booted up that there had been a problem other than the standard options MS Word gives you when a document closes suddenly.

On my way home from work I bought a new power supply unit. Is there anything else I should do, or should I just try installing the new power supply?

Thanks for any help you can give.

 

Greetings, shawnschirmer.

I think your best bet at this point is to install the new PSU - the "computer shuts down after half a second" symptom is common with failed power supplies.

That being said: the "brown crud on top of one of the mobo's capacitors" may very well be a sign that you have other problems - I've never heard of a case where a leaky capacitor fixed itself.

 

I think that is spot on, certainly looks like you have a PSU problem, and possibly a motherboard one too, that could have been caused by the faulty PSU, who knows. Put the new one in (I hope you bought one of a decent well known make) and see how things go, if you are still experiencing problems then post back with as many details as possible, but it doesn't look good for your MB.

 

Thanks very much to both of you. I'll try installing the new power supply (it's an Antec 500W 80 PLUS BRONZE, which should be more than enough to run my aging system if the PSU is indeed the problem) and will report back.

By the way, just so I can keep adding to what I know, what are the typical causes of the brown crud I mentioned on one of the mobo capacitors--is it age, or overheating, or something else...?

 

So I just installed the new PSU, but got exactly the same results: the fans start to spin, and in half a second the power shuts down completely. Just in case I also pulled the graphics card, modem card, and sound card (didn't realize I should have done that earlier), but nothing has changed. Any idea what my next step is?

By the way, in my original post I mentioned my computer shutting down on two occasions for no apparent reason in the days leading up to my current situation. Does that suggest a cause or diagnosis for my current situation?

Thanks,
Shawn

 

That ain't good.

You might try disconnecting the hard drive, removing and/or swapping any RAM modules, just to see if you can get a change in symptoms, but I'm leaning towards a faulty motherboard.

What's the make and model # of the motherboard?

 

It's a Gigabyte GA-K8NF-9 with nForce4-4x chipset.

So I've tried disconnecting the hd, but the exact same problems persist. I also tried the RAM in all combinations the mobo would accept, and then with no RAM at all (no substitutes available)--same sad story. Well, due to the help I've gotten here in narrowing the problem down I'm on the verge of splurging for a $60 replacement mobo from ebay. If that works (or doesn't!) I'll go ahead and work on my next build. In the last several years since I built my current machine I've lost track of what the best approach to a mid-priced build is. What do you think of the information in this article?

http://www.extremetech.com/article2/0,2845,2365957,00.asp

Thanks

 

I will definitely give this a try. Two questions, if you have a second--first, if the problem is that the arctic silver between the cpu and its heat sink isn't transmitting heat away from the cpu sufficiently, can the motherboard detect the processor overheating in literally half a second? My second question is, any time you pull the heat sink away from the cpu, should you automatically apply a fresh coat of arctic silver? Thanks.

 

For some reason my first reply to your post is going through the moderator. I'm assuming it'll show up shortly. If not I'll rewrite it.

 

Less is definitely more. But I think a pea-sized blob will result in a layer of thermal compound that is far thicker than it needs to be, and will probably result in excess thermal compound oozing out from under the base of the cooler and possibly shorting circuit components that are close to the CPU chip.

While thermal grease is designed to conduct heat, it doesn't do that anywhere near as well as the metal of the heatsink. Too much grease results in poor cooling. Thermal compound therefore should not be applied any more thickly than is necessary to fill the microscopic pores in the surface of the CPU and the base of the cooler. A couple of thousandths of an inch is ample. The thickness of a hair is too much.

Arctic Silver's instructions recommend a blob the size of an uncooked rice grain for a single-core CPU chip. Whether you're using Arctic Silver or not, their instructions are detailed and are worth looking at for the background information they provide. You can probably find instructions for your CPU at <http://www.arcticsilver.com/methods.html>.

 

Thanks very much for the advice, and for the link.

Burrell--what you mentioned about the earlier shutdowns makes sense. Could that have led to my computer's current condition? I don't see how it could, but then again I'm not expert in these matters.

Rob--I'll keep that very much in mind. I really appreciate advice that teaches.

So, when my new used mobo arrives, and after I connect it to all the hardware, will my computer boot up as it has in the past, or are there other steps I'll need to take, what with having installed a motherboard new to my hard drive and current OS (Windows XP)?

 

Is the replacement motherboard a Gigabyte GA-K8NF-9? If so, you might get away with a one-for-one install. If not, there may be additional drivers (especially chipset) that will need to be loaded.

Also, the possibility exists that you may have to re-validate your Windows. Shouldn't be a problem - it's been my experience that Microsoft is usually pretty understanding when it comes to replacement hardware.

 

I'm aiming to replace my Gigabyte GA-K8NF-9 with an identical board, but they're not that easy to find, especially new. I have seen a large number of mobos w 939 sockets, meaning they can handle my Athlon 64 3000 CPU, the 2 GBs of 184 pin DDR memory, the Nvidia 6600 I have in my current board, and other peripherals, so if the only thing I'll need to do is install drivers, then it sounds like I'll be all right for a while whether I go with a replacement GA-K8NF-9, or have to buy a comparable motherboard. Can you recommend the best book out there on building a system? When I built my current system I was able to find out what I needed to know over time and in piecemeal fashion. It would be great this time around to be able to have a solid, thorough source to work from.

Twice over the last three years I've had to zero out my HD, and the techs who validated my copy of XP never gave me a problem.

 

I personally don't know of any all-inclusive manuals for building a machine - I'm sure others here will chime in with some good links.

Frankly, though, I'm leery of such, because I see no way one reference could anticipate every real world situation. I don't like depending on something that may leave me hanging at a critical point - but that's me.

IMO, just use patience, common sense, and, of course, Major Geeks - there are some fine builders here who can help with any questions.

 

That makes sense. I appreciate all your help. (The replacement mobo I ordered has to come from China so it'll be a while before I can confirm whether that was the problem).

In the meantime, if you have time for one more question, can you give me your opinion on whether the $1,250 version of a DIY gaming rig in this article on the site ExtremeTech.com is a worthwhile system to build?

http://www.extremetech.com/article2/0,2845,2365963,00.asp

In case others are interested, the article seems very well done, and starts with a basic, $500 rig, gradually upgrading through six price points, and maxing out at $1,500. I don't know enough to judge how good the various systems are, but it seems like a great approach, to lead the reader through the various upgrades and what they are meant to accomplish.

Thank you.

 

Good morning.

ExtremeTech always offers good articles and information - been using them for years. That $1250 system is certain to be a screamer.

Of course, there are going to be differing opinions about components, and the adage about "'wait 'til tomorrow, the prices will come down" usually rings true. I think you're doing the right thing: if you're wanting to build a hot rod gaming rig, do your research!

Please let us know when you get your replacement board installed and how things work out - we'll be here. :major

 

Hey, I just wanted to share that I have had the same issue on my own PC. Constant random shutdowns after mere seconds and it turned out to be a faulty power switch. Just thought I would share this with you. Anyway, good luck with your repairs/new system.

 

Bluenose--
Thanks for the info. I've looked up replacing the switch and may give that a try before trying a new motherboard. Did you ever figure out, if the function of the switch is simply to get the power going, and since the power is om fact getting started, why a malfunctioning switch would then cause power to off? My guess at this point is, that once it got the power going, the switch itself shouldn't be the cause of of the power then shutting down completely. Any thoughts on that--did you ever figure out the nature of the malfunction in your case?

 

I appreciate all the help. I'll post again after I take the next step with my current rig. Also really looking forward to putting my next computer together. It's so much more satisfying than buying one already assembled!

 

Unfortunately, I didn't get to the very bottom of my power-switch issue. I had an engineer come to my home and he took the PC away. When he returned I was not in and didn't get an opportunity to talk with him about it. He did replace the wire that connects the button to the board though.

In my particular case, my PC would sometimes get to the desktop, once there it was actually going through the windows shutdown procedure, as if somebody was pressing the switch. That is, the soft switch that you would use, not the main power switch at the rear of the PC.

As my problem went on and on, the PC would shutdown 2 seconds after being turned on, then shut-off (as if someone pressed the button) then come back on (as if someone pressed the button) then shut-off (as if someone pressed the button) and on and on it went like this.

I am not sure how this compares to your problem that you have today.

 

Hm. I'm not sure how it compares, either. Then again, I don't grasp how the issue you had shut down your computer more and more frequently. On top of that, what with the various things I've tried, I've turned the power to my computer on about forty times and with the exact same result every single time. I'm not enough of an electrician to know what that might tell me, but a power switch is a $7 fix so it makes sense to give it a shot. My best guess is that either there's a short that the BIOS is detecting and therefore it's shutting off the power, or it's detecting some other malfunction and shutting off the power. Damned if I know what that other malfunction might be though. That's the problem when your nearest computer-savvy friend lives a couple of hundred miles away. There's a lack of spare parts to swap in and out of my case.

 

Yup. My point was only that it might be worth spending $7 on the switch first, and if that doesn't work replacing the mobo.