I built my own computer and a year later the PSU (500W) burnt, I bought a new PSU again ( coolmaster 700W ) and now ( 5 months later) it is burned again. What could be the cause? Did I improperly wire my computer ? or is it the power outlet?

I checked the ground connectivity with my multimeter and it looks well grounded ( low resistance and 3V approximatively).

I have 2 hard-drive, a 460 GeForce graphics card. and a Quad core.

Thank you

  • Can you be a bit more specific regarding the PSU, what model was it? What's the HDD brand and model, motherboard brand and model, and the amount of RAM modules? Also, any other hardware consuming from that PSU?
    – Zuul
    Commented Aug 9, 2012 at 19:20
  • Why? I listed all the necessary info, what would the model change? power is power, wether its modal A or B, 500W is 500W, no?
    – EEstud
    Commented Aug 9, 2012 at 19:37
  • 1
    Power is not only the 700W or the 500W, refer to Thermaltake Power Supply Calculator to get a clear picture of all the hardware involved for an appropriated power consumption calculation. And all that only gives you an educated guess :)
    – Zuul
    Commented Aug 9, 2012 at 19:42

2 Answers 2


This could happen due to any of the following reasons:

  • The Voltage is unstable in your area (maybe you could use a UPS/Voltage regulator?)

  • Might be something with the wall outlet as you mentioned

  • The PSU cannot handle the load of all the components u have installed on ur PC. Refer to the specs of each component and focus on their power consumption then, estimate your overall wattage needs. Graphics cards and processors can get really demanding especially if you have some overclocking going on.

  • The PSU energy efficiency rating isn't that high? Or, perhaps it is a "no brand" that is not really delivering the wattage it promised you on the box (Edit: You mentioned cooler master so, I guess that's not a valid point).

  • Ventilation/air flow, space and cable management issues causing the PSU to overheat.

  • The power cable itself might be problematic if it's not high quality with proper diameter and other specs. I can recall, I had a similar problem when I purchased a cable that didn't come with the PSU.

  • There's one that you've left off: "You've simply bought very poorly-made power supplies" (although Cooler Master generally aren't a problem...but generically it's an important point)
    – Shinrai
    Commented Aug 9, 2012 at 20:22
  • That's kinda embedded in my 4th point =). (Hint: no brand)
    – TjWallas
    Commented Aug 9, 2012 at 20:41
  • I guess I can read it that way, but IMO it's worth being explicit about. It doesn't have to be providing insufficient wattage (even as a percentage of what it's capable of, versus what is claimed) to fail as a result of shoddy components.
    – Shinrai
    Commented Aug 9, 2012 at 20:49

I've had this happen.

If there's a subtle short between the mains pins on the power supply, for example a bit of loose conductive material in the IEC "kettle" lead, it can short across the pins, causing arcing, burning smells, and eventually will destroy the PSU.

I speak from experience as this has happened before and melted the IEC lead, also caused the power supply to have to be replaced. This was in a Corsair VS550 PSU, but was the fault of the kettle lead not the PSU.

I did take photos of the destroyed kettle lead and burned PSU pins with burn marks and soot on them, i don't have them any more so here's a similar image of the damage:

Melted IEC "kettle" lead

As a preventative measure for this i now always run my PC through a cheap RCD, the sort you'd plug into your mower or hedge trimmer. This way any similar short in the future will cut the power before it can cause damage to the machine.

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