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[Solved] Power supply or motherboard

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  • Power Supplies
  • Motherboards
  • Components
Last response: in Components
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December 26, 2011 7:21:56 PM

I have an ASUS m2n-E mother board with an Enermax NoisetakerII which will not power up. The green light is lit on the mother board which suggests it is getting power and there were no sparks or such when I tried to power it up or when I powered it down. So my thinking is that the motherboard has quit working. is there any way to make sure which is bad?

More about : solved power supply motherboard

December 26, 2011 11:48:38 PM

This is not a new build. It was a running computer till I powered it down the other day :(  I did however make sure all the connections were reseated just in case
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December 27, 2011 11:18:51 AM

Did you do any work on the insides after switching it off yesterday? I've had similar symptoms years ago after installing an HDD and blowing the motherboard.

If that's not the case, have you had any stability issues with the PC lately? BSODs, random restarts, etc?
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December 27, 2011 8:22:40 PM

The only out of ordinary thing is the power got turned off on it(without a proper shutdown...I hate surge protector power switches). I left for the day came back pushed the power switch to turn it on and nothing happened. I opened it up afterwards to see if I could figure out what was going on. Noticed the green power led was on on the mother board then checked to make sure all the cables were good without success.

It is my understanding the power switch engages a relay on the mother board. So what I am trying to figure out is it the relay on the mother board or is it the actual power supply that has issues? Is there a way to check the power supply whithout the computer being booted up? I do have a pretty good multi meter and am not a complete idiot with it.
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December 28, 2011 11:11:40 AM

You can check the PSU using a multimeter. The following comes from link I posted:
shortstuff_mt said:

"The best way to check the PSU is to swap it with a known good PSU of similar capacity. Brand new, out of the box, untested does not count as a known good PSU. PSU's, like all components, can be DOA.

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. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

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.

tube_gdata ]http://www.youtube.com/watch?v=5FW [...] tube_gdata

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. You can carefully probe the pins from the back of the main power connector."


If the PSU passes this test then try to borrow a working motherboard and test that with the PSU.
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January 4, 2012 2:23:10 AM

Thank you for your help with the info you posted I was able to determine the power supply is working fine. The issue is with the mother board. When I shorted the green and black wires the power supply worked. It also caused the motherboard to start up but, it seems that relay that switches the power supply on is faulty. I was able to do a backup and copy some data off. So all is well in my world now...Well almost all...
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