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Computer won't start, running out of ideas what could be wrong.

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March 15, 2012 2:41:13 PM

Hello,

I'm having some recent problems with my fiancee's desktop and I'm running out of ideas what could possibly be wrong. She has had the computer since May of 2009 and we have never had any problems other than I've noticed that in the last few months load screens on some games have taken a few seconds longer, but nothing major. Last week however, I came home and started it up. I was playing a game and after about 20 minutes the computer just shut down. Thinking that was weird I tried to reboot it, but all it would do is attempt to start, go for a few seconds, and then the light would turn off, and it would try again. It would keep trying this until I pulled the plug (the original PSU does not have an external switch). I've had one PSU go out before so I started going through what could possibly be the problems.

First I tried a new, larger PSU but the same thing was going on. Thinking one of my parts could be bad I unhooked some things so that the only thing plugged into the PSU was the motherboard with only the CPU, heatsink fan, along with the speaker, power switch etc. I pulled the four sticks of memory, the video card as well as unplugged the HDD and the DVD drives.

When I started it up it would beep because there wasn't any memory, but would still turn off after anywhere from a few minutes to a few seconds and begin cycling again. I tried my memory and my video card in another computer and they worked fine, but I figured they were narrowed out of the equation since the problem is occurring without them anyway. Thinking it could be something with either the motherboard or the CPU, I began working through the list of things I could think of.

I replaced the CMOS battery and that let it start up and run for about 5 minutes (but that could be attributed to it sitting without being turned on for a full day) but eventually returned to the same problem. At this point I can't get to the BIOS. When I start up the computer with all parts hooked up, I get the typical one beep like a normal startup, but it turns itself off and starts resetting every few seconds.

Thinking it could be an issue with the CPU becoming loose or overheating somehow after it was moved a few months ago, I reseated the CPU and applied new thermal compound before sitting the heatsink back. This did not help either and I did make sure to check that no pins on the CPU were the problem. The CPU is an Intel Q8200 if that matters. The next thing I tried was to take the motherboard out thinking maybe it was shorting somehow, so I placed it on an insulated surface and hooked the bare minimum up again to try it, with the same failed results.

I'm really at a loss as to what could be wrong and what could even cause this because like I said, it had worked with absolutely no problems for over 2.5 years. I'm getting really frustrated by this because I've been forced to work on my laptop which is much slower and inconvenient.

Is there anything that someone can suggest that I can try? I've tried to do numerous searches but I can't seem to find an answer that has worked so far.
a b B Homebuilt system
March 15, 2012 10:40:16 PM

Check temps. A tool like 'realtemp' (google it) can help. Rule out thermal throttling. Blow away dust from everything with a can of compressed air.

You've replaced the power supply. Good thought, didn't help.

Inspect the MB for blown capacitors. http://en.wikipedia.org/wiki/Capacitor_plague

Wire could have become crimped/frayed in the case, shorting. Visually inspect.

You probably reset the bios to factory default values and saved after you replaced the CMOS battery. If not, do so. Make sure you save.

Follow the adivce here. It's for new builds but a lot will apply to your system. http://www.tomshardware.com/forum/261145-31-perform-ste...

Good Luck. P.s. if it doesn't fix now is a GREAT time to be buying a computer. Strong CPUs, low power, mostly cheap parts (except HDDs)
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March 16, 2012 7:12:33 AM

I've cleaned out the whole case and used compressed air to get dust out of the way. While I had the motherboard out I made sure to inspect it and didn't see anything out of the ordinary. I don't think I'm going to be able to check temps or reset the bios because as I said, for the last week I've only been able to get it to stay powered on in an attempt to boot up for about 5 seconds typically. I looked through that list before posting because I've been trying to get this fixed for over a week now. Is it possible that the motherboard just went bad for some reason? It seems like I've tried to make every other change and so far I haven't seen any improvement.
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a b B Homebuilt system
March 16, 2012 9:15:04 PM

Very possible the MB died. This is the new one you got? The failure rate for electronics is high when first turned on, then falls off to a reasonable level.

When you RMA the MB they'll probably want to walk you thru some debugging discussion which can't hurt.

EDIT: Ignore above comment, I have no clue why I thought you tried a new mb.
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March 17, 2012 3:27:40 PM

tsnor said:
Very possible the MB died. This is the new one you got? The failure rate for electronics is high when first turned on, then falls off to a reasonable level.

When you RMA the MB they'll probably want to walk you thru some debugging discussion which can't hurt.


I haven't tried a new MB yet. I was hoping it wouldn't come to that point. The board is original so approaching 3 years old so obviously won't be able to RMA it so I guess the next step will be to either find a compatible replacement board or start researching for a new computer to build.
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a b B Homebuilt system
March 18, 2012 11:47:39 PM

"I've only been able to get it to stay powered on in an attempt to boot up for about 5 seconds typically."

This is with just the CPU, MB and power supply. No memory, PCI card, etc. Make sure the MB is not connected to the case power supply button. If those fail you can see this kind of three second shutdown. Early in the thread before you pulled the MB yu had "so that the only thing plugged into the PSU was the motherboard with only the CPU, heatsink fan, along with the speaker, power switch etc." make sure to remove the power switch wire. The FAQ has section on what to short for an instant to start a PC

You tried a new power supply. "First I tried a new, larger PSU but the same thing was going on." Have you tried both power supplies in this configuration? That would seem to rule out the power supply.

"I reseated the CPU and applied new thermal compound before sitting the heatsink back." CPU overheating would also cause this problem, but you've already ruled this out.

Looking to me like MB, but maybe someone else can post opinion.

EDIT: ok, one more. Where is the line cord from the PSU plugged? Into a surge protector? Into a UPS? Into the wall? If it's not direct to the wall then move the PC somewhere else. A problem with the UPS or surgeprotector can show up this way.... (OK, this is reaching, but it's cheap to test. I actually hope it's the pc's switch).
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March 19, 2012 2:37:42 PM

Thanks for the help. Even without the memory and PCI card in the computer will shut down in a few seconds and cycle. I've tried both PSU units with the breadboarded MB so I don't think it's a PSU issue. Originally the computer was plugged into a UPS, but while trying to figure it out I've moved the case into an area that is better lit and have the PSU plugged directly into the wall. I'll see if I can short it tonight and see if it will start to test the switch, but I'm not expecting much success.
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March 29, 2012 3:59:58 PM

Sorry for the late reply, I had to go out of town for a last minute business trip and was unable to work on my computer while away. When I got back I tried shorting it to see if was the switch but it didn't help. I guess my next thing will be to try a new MB. At this point I'm not sure what else it could be.
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a b B Homebuilt system
April 5, 2012 8:52:41 PM

me neither, you've tried everthing I would have and more. Maybe someone else has an idea. Good luck.
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