Computer shuts down after a few seconds

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Slush69

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Hi

Some days ago I couldn't start my computer. When I pressed the power button nothing happened. So I disconnected everything, opened the case and checked each connection. After a few tries, I could power it up. It ran for half a minute before I shut down again because neither my keybord nor monitor were attached.

I reassembled the case and connected everything. Once again it would not start.

So I opened it again and checked everything. I suspected that it might just be a PSU problem although the LED on my motherboard was on. Despite going through the same steps as before it would not start. Then I removed the motherboard battery, waited for 10 minutes, reinserted it. Still no joy. I also manually shorted the power on pin, but it did not help either.

Today I bought a new PSU and installed it. After reconnecting monitor, mouse and keyboard I turned it on and it worked. My screen displayed a BIOS error message that's probably due to the battery I removed and reinserted.

To my dismay the computer shut down after 30 seconds and restarted. After 5-10 seconds it restarted again and so on until I pulled the plug.

I can see that all cabinet fans and the CPU fan is running during startup, but my graphics card fan is not.

Although I don't find it likely that both my PSU and graphics card would give up at the same time, I suspect that the graphics card might have a fan failure, and that my computer now automatically shuts off when the GPU reaches a critical temperature. Does that sound likely?

Any ideas or input are very welcome.

SYSTEM INFO
Home built
Core 2 Duo E6600
4 MB DDR2 RAM
Geforce 8800 GT card
Asus P5K Motherboard

Thanks,

Slush69
 

mrbobc

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do you get any odd beeps when you switch it on?? do you get any beeps at all?

i'd suggest reseating you gpu, followed by trying 1 memory stick at a time, then maybe reseat you cpu if you've recently installed it yourself. check that your power connectors to your gpu work too!
 
I doubt the GFX card could overheat that quickly in text mode; CPU could though...

It sounds like the CPU is either overheating or not getting enough juice. Try loading into the BIOS (DONT TOUCH ANYTHING UNTIL YOU KNOW YOU ARE STABLE) and see if the computer can hold there...
 

JPunisher

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I had similar problem, look in case for anything that can short. eg Fan wires, wrong plugin or something. Next Replace your RAM modules, not go buy new ones. Just take out and put back in. Take out your G-card and see if it boots, if it does then you know that it is your G-card =D
 

Slush69

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Hi

I reshuffled the RAM modules, and double checked all connections including the graphics card. Then I loaded into BIOS.

The computer booted nicely into the BIOS setup. I could see all fans running - including the CPU fan - after a short while the GPU fan also started. After approximately 2 minutes the computer shut down again and started a cycle of constant restarts until I pulled the plug.

The new PSU (a NorthQ 550W) should provide amble juice, so I suspect there might be an overheat problem despite all fans working as they should. Before all this the system had been running stable for over a year.

I'm pretty sure the problem is either with the CPU or the graphics card, I just don't know which.

rgds/slush
 

Slush69

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UPDATE:

I loaded into the BIOS again and went to the power menu to monitor the CPU temperature measured by the motherboard.

It stayed on a stable 25 C before the computer shut down again.
 

Slush69

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UPDATE II:

Hoping for a cheap and easy solution I bought and installed a new CPU heatsink and fan. It did not solve the problem. Does anyone here know whether an ASUS P5K monitors graphics card temperatures and shuts down if the card overheats?
 
You won't be shutting down due to overheating at 25C, although I have the feeling thats a busted sensor (or your using a REALLY GOOD watercooling setup...using liquid nitrogen...)

I'm leaning towards the board itself at this point. GPU shouldn't be an issue in text mode, especially if there is no distortions. You tried a new CPU/PSU. That leaves the mobo itself and RAM, and I doubt RAM could ever get to the point where sitting in the BIOS could cause a restart...
 

Slush69

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No liquid nitrogen here. :D

I suspect you're right. It may very well be the mobo. What baffles me, though, is that the problem seems to have all the hallmarks of a heat problem. When the computer's cold it stays on for several minutes, all subsequent restart cycles are 10-20 seconds. If I leave the computer turned off for 5 minutes or so, it will start but only for 30-60 seconds. Something's either cooling off or slowly discharging.

rgds/slush
 

Slush69

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I don't believe this. I bought a new motherboard, ASUS P5Q, installed everything and now I'm back at square one.

The motherboard LED shows it gets juice, but when I press the power button nothing happens. After 5 seconds or so, I can hear a clicking sound from the PSU
 

Slush69

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Sorry, I was a bit quick on the trigger there and made a daft mistake. In the heat of battle I managed to connect the PCI powercord to the ATX on the mobo ...

I sorted it out and reset the correct power cords.

When I started the computer it behaved in the exact same way: I could enter the BIOS setup and poke around there for a minute or so, then it shut down and went into the restart-shutdown cycle.

Conclusion: There was nothing wrong with my old motherboard, the problem is somewhere else.

It might be the CPU, but my guess is that if it's fried I shouldn't be able to access the BIOS at all. I'm really at a loss here ...

 

Slush69

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Update: I disconnected the graphics card and the computer stayed on. So I thought: Oh, great. I just need a new graphics card then. I bought one, installed it, turned on the computer and ... it shut down after a minute.

Ok, then there's really only the CPU left. It's the last thing I have not replaced. So I thought: Oh, great I just need a new CPU then. I borrowed one (wiser, see?), installed it, turned on the computer and ... it shut down after a minute.

Now I'm at the point where I suspect it's my new PSU that's causing the problem.
 

Slush69

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SOLVED:

It turns out the new PSU I bought was faulty. I installed a new one and now everything's back to normal.

Thanks for the help from everyone who chipped in!
 
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