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Sudden Power Loss

Last response: in Components
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September 1, 2009 4:30:26 PM

Hello,

I've got a pretty bad problem with my rig. A week ago it started cutting out on me.

The computer was running fine, under no real load (web surfing, etc) and then the power would cut out as if the power cord was pulled from the back. The rig would restart when I pressed the power button but the issue has persisted. Sometimes it hits within 5 minutes of boot, other times it can run fine for six hours.

It doesn't seem to be a temperature issue, nothing seems out of the proper range and I've been running the computer with the case open to check it.

Nor does it seem to be a problem with the RAM as I have swapped out all my sticks and still suffer from the power loss.

I even tested the voltages on the PSU with a multimeter and I couldn't see anything wrong with the readings (Although I have never tried testing a PSU in this manner before).

So I have no idea whats going on and would really, really appreciate some help.

All the relevant parts are still under warrenty but I'd need to know what part was causing the issue before sending them in.

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a c 144 ) Power supply
September 1, 2009 7:23:02 PM

I'd start with the PSU. I'd try to test it elsewhere.

The following is a cut and paste from a previous thread:


Try to verify (as well as you can) that the PSU works. If you have a multimeter, you can do a rough checkout of a PSU using the "paper clip trick". You plug the bare PSU into the wall. Insert a paper clip into the green wire pin and one of the black wire pins beside it. That's how the case power switch works. It applies a ground to the green wire. Turn on the PSU and the fan should spin up. If it doesn't, the PSU is dead.

If you have a multimeter, you can check all the outputs. Yellow wires should be 12 volts, red 5 volts, orange 3.3 volts, blue wire -12 volts, purple wire is the 5 volt standby. They can be checked in operation from the back of the main power plug.

The gray wire is really important. It sends a control signal called something like "PowerOK" from the PSU to the motherboard. It should go from 0 volts to about 5 volts within a half second of pressing the case power switch. If you do not have this signal, your computer will not boot. The tolerances should be +/- 5%. If not, the PSU is bad.

Unfortunately (yes, there's a "gotcha"), passing all the above does not mean that the PSU is good. It's not being tested under any kind of load. But if the fan doesn't turn on, the PSU is dead.
September 2, 2009 8:29:14 AM

Thanks for the reply.

I have already tested the voltages with a multimeter but it is interesting to note that the other thread says that doesn't mean the PSU is okay even if it passes.

My gut instinct tells me its the PSU and I'm getting to the point of just RMA'ing it but if anyone has any other ideas before I do I'd be greatful.
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September 2, 2009 8:51:25 AM

It seems a cold solder in the PSU.
September 2, 2009 8:58:12 AM

you might have a dodgy motherboard..but I would suspect the PSU first...
If the PSU is good then RMA the board ASAP as the warranty has restrictions.

Hope this helps..JQ
!