Pc powers ups very briefly and shuts off

biscuit_247

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Oct 8, 2008
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I know this has happened with a few people and I need a solution badly.

my computer froze. I shut it down and now it won't even power on. I keep flipping the switch on the back of the psu it started than shut off very quickly Installed a new psu not luck. took out all memory sticks but one disconnected drives and video card out still no luck. When I disconnect the cpu power the pc stays on. What is wrong?

specs:
Gigabyte gigabyte ga-ep45-ud3p
8 gigs of ram
q6600 2.4
thermal take 600w
5770 ati radeon xfx
2 1.5 tb seagate
2 160gb western digital
zalman 9500 heatsink
 

westom

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Mar 30, 2009
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You have two choices. Just keep replacing good parts until something works - as you are doing. Or post facts so that the better informed can then post conclusions that contain no speculation.

The latter means buying or borrowing a digital multimeter. Set to 20 VDC. Measure the purple wire where it connects the PSU to the motherboard (disconnect nothing; change nothing; leave power cord connected to AC). It should report about 5 VDC. The actual number must be reported to 3 digits.

Do same with the green and gray wires both before and when the power switch is pressed. Again, post those numbers.

And finally monitor any one red, orange, and yellow wire as the power switch is pressed. Report that (if any) changes.

Only then will the next reply actually answer your question. Your responses will only be as useful as facts you first provide. Currently no useful facts are provided (other than it does not power on). A useful reply can not happen until you first provide those numbers.

Or just keep replacing good parts until something works.

 

eslagle23

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Sep 9, 2011
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Hey Westom, I was reading your reply here as I have the same problem with my new build flashing on and powering off right away. I went ahead and recorded the power readings for all specified wires, and they are as follows:

Note: In between each reading I flipped PSU switch on/off.

Purple wire - 5.05 VDC sitting idle. When power switch pressed, no change.

Green wire - 4.14 VDC sitting idle. when power switch pressed, decreases to .33 and holds there.

Gray wire - 0.00 idle, and after pressing power switch.

Red wire - 0.00 idle. When power switch pressed flashes 0.88 and drops back down to 0.00

Yellow wire - 0.00 idle. When power switch pressed jumps to 2.54 and slowly back down to 0.00

Orange wire - 0.03 idle. when power switch pressed jumps to 0.69 and slowly back down to 0.03.


I hope you're still monitoring this thread, any help would be greatly appreciated. Thanks!