Possible short shutting down my computer!

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Possible short shutting down my computer!

Postposted on Mon Jul 05, 2010 11:41 pm

Hello all,

I've been having power issues recently with my home computer regarding it shutting down instantly and without warning. I opened my computer and found that one of the expansion slot caps and had fallen out, since it was not screwed down, onto the metal backing of one of my two video cards. I removed this cap and screwed it back into place to close off the expansion port slot in the back. Well, that seemed to work, I even checked my power supply with a multi-meter and was getting constant +12/+5 volt readings from one of the molex end pieces.

That worked for about a week. Today, my system mysteriously shut down again. And it won't stay on for more than a few seconds until it just shuts down as if being shorted out. I found that one motherboard mounts didn't have a screw, so I put one there, but still the same power downs. I'm planning to pull all the add-on cards and memory and start from scratch to see if maybe one of them is causing this problem. If not, I will dissassemble the entire machine and maticulously rebuild it and hope for the best. I've checked for leaky caps, but haven't seen anything overly odd.

One thing I remember doing about a year ago...I was replacing the northbridge heatsink/fan when my screw-driver slipped and jammed into the surface of the motherboard...the screw-driver knocked off a tiny rectangular deal that was soldered in place there...it was very tiny. At the time, though, the computer worked fine so I thought well maybe I hadn't really damaged much.

At any rate, if anyone has a thought or two regarding this I would appreciate that very much.

Trellot
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Re: Possible short shutting down my computer!

Postposted on Tue Jul 06, 2010 12:46 am

Have fun.
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Re: Possible short shutting down my computer!

Postposted on Tue Jul 06, 2010 1:56 am

I think this might be a case of your mistakes catching up with you, by dropping and knocking things. Still go about it methodically. I'm interested to know what you find.

By the way, the green text in your signature is unreadable on my screen (an IPS panel) unless I highlight it. If you want people to read it, you should change the color to something more readable.
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Re: Possible short shutting down my computer!

Postposted on Tue Jul 06, 2010 1:37 pm

There are so many possible culprits here, it is hard to say what is most likely. The slot cover falling onto the video card, and the component you dislodged from the motherboard are both potential culprits. It is also possible that the PSU, motherboard, or some other component is dying for reasons completely unrelated to either of the mishaps you mentioned.

Basically, you're just going to have to go by process of elimination.

I would try removing the video card you may have shorted out first. Then try a different PSU. If neither of those things help, strip it down and rebuild it piecemeal, like you mentioned in your original post.

Also, you mentioned there was a missing motherboard mounting screw. I don't think that would cause any issues, but a related (and potentially much more serious) potential problem is an extra motherboard mounting post underneath the motherboard. Are you absolutely certain that all of the posts match up with holes in the motherboard? If there's a post that isn't under a hole, it could be shorting out to the back of the motherboard.
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Re: Possible short shutting down my computer!

Postposted on Wed Jul 07, 2010 10:56 pm

just brew it! wrote:If there's a post that isn't under a hole, it could be shorting out to the back of the motherboard.
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Re: Possible short shutting down my computer!

Postposted on Thu Jul 08, 2010 12:22 am

Trellot wrote:
just brew it! wrote:If there's a post that isn't under a hole, it could be shorting out to the back of the motherboard.


I will check for this...very interesting. However, here is an update on where things stand: After I removed my two video cards, my sound card and two memory modules, I fired up the rig and it powered down or rather "snapped" off which is a better description. The only thing still plugged into the motherboard were my two hard drive SATA connections, two dvd roms and a 3.5 floppy drive. Now I am dismantling the entire unit, including the motherboard and will start over rebuilding the thing from scratch, testing at each stage. I do not have a spare PSU to check my current one unfortunately, but like I said my tests indicated a strong 12/5 volt reading with no fluctuations...course I only tested one molex connector. One thing I did notice while dismantling the 3.5 floppy drive was that the cable was slightly torn near the drive connection...not sure if that would do anything?

I will update again as I progress.

Trellot
-ASRock Z68 Extreme3 Gen3 LGA 1155 Intel Z68 / Intel Core i5-2500K
-XFX Radeon HD 7970 3072MB, GDDR5, PCI-Express 3.0
-Corsair Enthusiast Series TX850 V2 PSU / Corsair 600T case
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Re: Possible short shutting down my computer!

Postposted on Thu Jul 08, 2010 12:52 am

If it's turning on and shutting down, that points to either the motherboard or the PSU. It's still possible to be something else, but I'd focus on those.
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Re: Possible short shutting down my computer!

Postposted on Thu Jul 08, 2010 7:22 am

Try assembling it barebones outside the case (just the motherboard, PSU, CPU, RAM and video card). You can then attempt to power it up by shorting the power switch pins on the motherboard header with the tip of a screwdriver.

I don't think a damaged floppy cable would cause the symptoms you're seeing. I agree with FireGryphon -- sounds like PSU or motherboard to me. I've had multiple PSUs that caused exactly the symptoms you describe when they died. (And all of them were ThermalTake. What brand is yours?) You might save yourself a ton of trouble if you can borrow a spare PSU from someone to try; it would be pretty annoying to tear the whole thing down, and then discover it was the PSU all along!
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Re: Possible short shutting down my computer!

Postposted on Thu Jul 08, 2010 9:50 pm

My PSU brand is OCZ. Here's what I've done: First, I went ahead and dismantled the entire thing and even extracted the motherboard. I did not notice any extra motherboard mounting screws underneath, so that's fine. I then placed my motherboard on a piece of cardboard, plugged in the PSU and fired it up...only it did the same thing, no power up!

At this point with the motherboard completely separated from the case, there aren't any intermittant connection issues with the case itself or some other unkown object. So, like you've all said, it must be either the PSU or motherboard. However, might the connected CPU still potentionally play a role in this thing? I don't know.

I guess I'll go back and test every rail coming off the PSU with my friend's multi-tester. Here's one thing...when I turn on the PSU while it's connected to the motherboard, two lights light up on the board and stay on even while the motherboard won't power up...so the board is getting power. Would this lead us more toward the motherboard being the issue? Of course, at the same time, the motherboard obviously is able to except this power trickle and light up those lights, so it looks perhaps like a draw...sigh. :-?

Trellot
-ASRock Z68 Extreme3 Gen3 LGA 1155 Intel Z68 / Intel Core i5-2500K
-XFX Radeon HD 7970 3072MB, GDDR5, PCI-Express 3.0
-Corsair Enthusiast Series TX850 V2 PSU / Corsair 600T case
-G.SKILL Ripjaws X Series 16GB / Hitachi Deskstar 750GB
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Re: Possible short shutting down my computer!

Postposted on Thu Jul 08, 2010 10:18 pm

FireGryphon wrote:By the way, the green text in your signature is unreadable on my screen (an IPS panel) unless I highlight it. If you want people to read it, you should change the color to something more readable.


Changed it to black. Hope that helps the issue.

Thanks,

Trellot
-ASRock Z68 Extreme3 Gen3 LGA 1155 Intel Z68 / Intel Core i5-2500K
-XFX Radeon HD 7970 3072MB, GDDR5, PCI-Express 3.0
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-G.SKILL Ripjaws X Series 16GB / Hitachi Deskstar 750GB
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Re: Possible short shutting down my computer!

Postposted on Fri Jul 09, 2010 8:21 am

Trellot wrote:Here's one thing...when I turn on the PSU while it's connected to the motherboard, two lights light up on the board and stay on even while the motherboard won't power up...so the board is getting power. Would this lead us more toward the motherboard being the issue?

The lights aren't conclusive one way or the other. All it tells us for certain is that the +5V standby rail (which is always on) is OK.
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Re: Possible short shutting down my computer!

Postposted on Fri Jul 09, 2010 11:00 am

At this point it still seems to be either motherboard or PSU, so not much different. You probably need to find a spare (borrow a friend or take it to a shop) of either to confirm. However, assuming your OCZ is a relatively recent good quality unit, I do have a slight leaning on the motherboard now.

Trellot wrote:
FireGryphon wrote:By the way, the green text in your signature is unreadable on my screen (an IPS panel) unless I highlight it. If you want people to read it, you should change the color to something more readable.


Changed it to black. Hope that helps the issue.
Just don't try to be cute with colours and let the theme (whatever the reader sets it to) take care of it. ;)
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Re: Possible short shutting down my computer!

Postposted on Sat Jul 10, 2010 9:43 pm

Alright. I've nailed it down to the PSU. I used my new Rexus power supply tester I purchased from newegg and it read that one of the 12volt connections was non-existent. Here's the model power supply tester I used:
http://www.newegg.com/Product/Product.aspx?Item=N82E16899705003&cm_re=Power_Supply_Tester-_-99-705-003-_-Product

I'm glad I didn't go out for a new motherboard or who knows what else thinking that was the problem. Thanks everyone for all of your comments. I definitely appreciate them!

Trellot
-ASRock Z68 Extreme3 Gen3 LGA 1155 Intel Z68 / Intel Core i5-2500K
-XFX Radeon HD 7970 3072MB, GDDR5, PCI-Express 3.0
-Corsair Enthusiast Series TX850 V2 PSU / Corsair 600T case
-G.SKILL Ripjaws X Series 16GB / Hitachi Deskstar 750GB
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Re: Possible short shutting down my computer!

Postposted on Sat Jul 10, 2010 9:49 pm

Flying Fox wrote:At this point it still seems to be either motherboard or PSU, so not much different. You probably need to find a spare (borrow a friend or take it to a shop) of either to confirm. However, assuming your OCZ is a relatively recent good quality unit, I do have a slight leaning on the motherboard now.

Trellot wrote:
FireGryphon wrote:By the way, the green text in your signature is unreadable on my screen (an IPS panel) unless I highlight it. If you want people to read it, you should change the color to something more readable.


Changed it to black. Hope that helps the issue.
Just don't try to be cute with colours and let the theme (whatever the reader sets it to) take care of it. ;)


Gotcha. Course I had it green for nearly five years and this was the first time anyone mentioned it. Btw, FireGryphon mentioned viewing this site from an IPS panel...what is that, exactly?

Anyway, take care everyone!

Trellot
-ASRock Z68 Extreme3 Gen3 LGA 1155 Intel Z68 / Intel Core i5-2500K
-XFX Radeon HD 7970 3072MB, GDDR5, PCI-Express 3.0
-Corsair Enthusiast Series TX850 V2 PSU / Corsair 600T case
-G.SKILL Ripjaws X Series 16GB / Hitachi Deskstar 750GB
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Re: Possible short shutting down my computer!

Postposted on Sun Jul 11, 2010 11:10 pm

One more thing...this power supply issue also explains why my WD Raptor drive had begun to BSOD every now and again, due to being a member of that failed power rail, just before the PSU failed completely. Now, that I've got my new Antec 650w PSU installed, all is very well again. :)

Trellot
-ASRock Z68 Extreme3 Gen3 LGA 1155 Intel Z68 / Intel Core i5-2500K
-XFX Radeon HD 7970 3072MB, GDDR5, PCI-Express 3.0
-Corsair Enthusiast Series TX850 V2 PSU / Corsair 600T case
-G.SKILL Ripjaws X Series 16GB / Hitachi Deskstar 750GB
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