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Random Power Failures

By twisted_sketch777 ·
I've got a problem with a recent build. The power shuts off randomly - sometimes it will just cut out when I nudge the case with my foot, sometimes not. Other people have reported that it sometims cuts out without any touching. This even kept happening after adding a UPS unit. Today, when I tried to turn it on, it wouldn't turn on at first - I gave the button several good presses, and as I pulled it foreward about an inch it just came on.

I looked inside. All fans are working, all power cables are well-connected. The power supply is a Seasonic S12, and the CPU is an Athlon 64 X2 3800. PC Probe II reports that the CPU and power supply are both running around 48-50 degrees C, and the mobo is running at a steady 38-39 degrees C.

The computer sits under a desk, and typically there's a few inches of breathing room in the back. It's sitting on top of a wooden panel to protect it from static on the carpet.

Any idea what the problem might be before I have to exchange the power supply?

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by TheChas In reply to Random Power Failures

Intermittent connections can show up just about anywhere.

With what you are seeing on this system, I would open up the case and do a little bit of investigation to track the source down.

Use the plastic handle of a screwdriver as a tap hammer. Use gentle taps rather than sharp blows to track down the source.

Start with the power supply itself. If tapping the power supply case causes the system to restart, odds are there is a bad solder connection inside the power supply.

Next, tap on the motherboard near the power connector. If a tap to the system board causes a reboot, check for long leads on the back of the motherboard that might touch the case.

Check the plug-in cards. I have had a number of systems where an AGP card has come out of the slot just a little bit causing system problems.

Don't ignore cables and power cords.


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by HAL 9000 Moderator In reply to Random Power Failures

It's also possible if the unit is in an enclosed space that the heated air blown out of the case is getting sucked back in and allowing things to overheat and stopping the PS.

I've seen M'Boards that are faulty but apparently work perfectly do exactly the same thing. The trick here is if it doesn't start immediately change the M'Board with a new replacement one. I don't know why it is so but I've now seen several M'Boards do this and I've had to replace every one of them. If there is a 2 charterer digital display on the M'Board it will be very helpful to see what it is displaying on Start Up and this will tell you what is going wrong.

Since this is a new build I would check everything first and also look for a trapped lead that may be earthing out this will also cause the same problem or even a lead that has been touching a fan that can touch the chassis will also cause problems like this. But remove everything but the M'Board, HDD, any fitted Optical, CPU & its Heat Sink and refit before you do anything else as it just may be something not sitting correctly. I've seen the new PCI Express Video Cards cause the same problem as they can partially work their way out and whenever the Video lead is moved it can cause the shutdown of the computer. These cards don't have a locking device on them like most of the AGP ones had so if the M'Board isn't mounted perfectly or the case is slightly out of spec they can marginally lift out and cause the connection to break whenever they get slightly moved.


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by jomar_venturuzo In reply to Random Power Failures
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by CLIFFL In reply to Random Power Failures

Start at the very beginning.
Check the obvious, the mains plugs.
Ensure the wires in the plug are not loose, obvious I know but it caught me out once.
Then replace the mains cables with known good ones incase of a break in the cable.
When you are happy that all external cables are ok then its down to the pc itself.
Should not be too hard to track down.

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by dallen In reply to Random Power Failures

Sounds like the power supply to me. Either it's faulty or not powerful enough. I've never heard of that brand of power supply, but I certainly wouldn't skimp when it comes to quality. Get a good named brand (like Antec), and I would get at least 450+ watts.

I hope this helps.

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