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Computer shuts down and restart again and again

Last response: in Components
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April 18, 2010 1:35:16 AM

Hello,
My computer shuts down and tries to resrtart, shuts down and tries to restart. I have taken everything out except for cpu and cpu fan. It still does it. When I disconnect the 4 pin ATX wire it will continue running. Once I reconnect the 4 pin wire it does it all over again. The comp wont start at all.

More about : computer shuts restart

a b ) Power supply
a c 159 à CPUs
April 18, 2010 9:59:26 AM

One fellow changed his outlet breaker to get rid of this problem. I would also try each ram stick individually to see if one is bad. List your board and power supply specs, and you might get more responses.
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a c 144 ) Power supply
a c 172 à CPUs
April 18, 2010 10:03:56 AM

System specs?

Probably either the PSU or motherboard is faulty or you may have a short circuit in the computer.

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
yes?

I mean work through, not just read over it.

Breadboard - that will isolate any kind of case problem including case shorts.
http://www.tomshardware.com/forum/262730-31-breadboardi...
Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.
You do have a case speaker installed, right? If not, you really, really need one. If you case or motherboard didn't come with a system speaker you can buy one here:
http://www.cwc-group.com/casp.html

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to.

You should hear a series of long, single beeps indicating memory problems.
Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU.

So, the best bet is to replace the PSU with a known good one of similar power capacity. Brand new, out of the box, untested does not count as a known good PSU.

Next best thing is to get (or borrow) a digital multimeter and check the PSU.

Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

Disconnecting the CPU power cable (that 4 pin cable) does two things. It removes the power from the power regulator on the motherboard that provides power to the CPU (CPU does not work). And it sinificantly reduces the load on the PSU.
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Related resources
a c 126 ) Power supply
a c 141 à CPUs
April 18, 2010 8:59:45 PM

A shorted power switch will do this, but there are other causes too, so go through ^their^ breadboarding suggestions.
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April 25, 2010 1:53:34 PM

o1die said:
One fellow changed his outlet breaker to get rid of this problem. I would also try each ram stick individually to see if one is bad. List your board and power supply specs, and you might get more responses.



You hit the chip on the head, It was a bad Ram Chip.
Thank you all for your help.

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