Recently built computer, PSU fused after ~3 hours, cooling fan fried?


I have recently built my first system, the main components are an AMD Phenom X6 1055T processor on an Asus M4A89TD PRO USB3 Motherboard. I have only 1HDD and 1DVD drive connected via SATA, on Win7 OS. This is powered with a 550W ATX Silent Neon PSU.

Last night, while internet browsing, there was a loud bang and spark from the back, which I think was near or within the PSU. The system immediately died, and will not power up again.

Whilst looking for reasons for this, I have found that one of the case fans is rated with a 12V input of 0.22A. The PSU kicks out 0.3A @ 12V. I have tested this, and there is resistance between the +ve and -ve connectors (AND the earth), which indicates to me that something has blown, and that the fuse (if there is one) did not protect the circuit.

I have also tested the inputs of the PSU (there is resistance between all pins) and the outputs of the PSU (there is little / no resistance, which indicates that the outputs are normal).


1/ Is it likely that I've destroyed the PSU?
2/ For safety's sake, should I buy a new PSU? Will this be the only repair I need to make? I have no other PSU that I could try (except perhaps an ancient 350W, with no SATAs).
3/ How likely is it that motherboard and processor will have suffered damage, and is there any way of checking for this? I can see no black marks on any connectors, and there was no burning smell immediately after the blowout.

I do have a reasonable grasp or electronics, and many multimeters, so I can test it if someone can explain how!

Many thanks in advance,

3 answers Last reply
More about recently built computer fused hours cooling fried
  1. Cheap generic PSU´s do not need help to blow. Replacement should come from Antec, Corsair, Seasonic or Enermax to name few manufacturers.
  2. Use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. 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.

    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.
  3. Odds are, the PSU went, meaning its probably a cheapo brand. That also means that odds are, other components are fried.

    Get a replacement CPU, and start testing each component one by one. If you're lucky, most of the important (expensive) items escaped unscathed.
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