Why did my PSU go bang?

[Guest Mesa]

24hours ago my Coolermaster Real Power 1250W PSU went bang. Very loudly. It tripped the fuse and everything in the room went off. It was 13 months old.Today I replaced it with a Corsair HX1000W and was as relieved as I've ever been that nothing else was damaged. The Corsair is much, much, MUCH quieter and being modular takes up much less room in my case - the Coolermaster was like a pair of mating octopuses!However, I really need to know why the Coolermaster blew like that. My whole system is on a Belkin surge protected extension lead which should rule out a power spike. I know there could be any number of reasons but I am now terrified that the new one will do the same sooner or later and I'm just sitting here waiting for the bang. Was it just a faulty unit? A bad component? Was it incorrectly installed? Was I just unlucky? I thought I could smell burning plastic the day before it happened but I ignored it. I'd appreciate any theories you might have so as to put my mind at rest!Thank you.

[TechguyMaxC 516]

Most home circuits can only handle 20A. A 1250W PSU could trip this. Also, power supplies do die.

[Guest Mesa]

Most home circuits can only handle 20A. A 1250W PSU could trip this. Also, power supplies do die.

The PSU on my last PC died but that was after 5 years of pretty intensive use. But after a year? I wasn't doing anything intensive at the time, nothing on my system is overclocked. I guess it was just a faulty capacitor?

[sargeski 16]

Most home circuits can only handle 20A. A 1250W PSU could trip this.

TechguyMaxC,Where did you learn how to do your math? 10A on a 120V circuit is 1200W. A 1250W power supply by itself is hardly enough load to trip a 20A circuit. Tripping a 20A circuit and the power supply failure are totally unrelated unless of course the 20A circuit was tripped as a result of the power supply failure. Mesa,I can pretty much guarantee you that if you heard a load bang from the power supply when it died, that a capacitor did indeed fail. Open up the failed power supply, if it made as loud a bang as you say it will be very easy to spot the failed component.Regards,Bob

[TechguyMaxC 516]

TechguyMaxC,Where did you learn how to do your math? 10A on a 120V circuit is 1200W. A 1250W power supply by itself is hardly enough load to trip a 20A circuit. Tripping a 20A circuit and the power supply failure are totally unrelated unless of course the 20A circuit was tripped as a result of the power supply failure.

I learned how to do math in the real world, where products are actually used. Can't say I've ever seen a dedicated "computer" circuit on a switch box... My point is: there are lots of other power draws in a home, especially on the typical "lights" circuit most people plug their PCs into.

[sargeski 16]

I learned how to do math in the real world, where products are actually used. Can't say I've ever seen a dedicated "computer" circuit on a switch box... My point is: there are lots of other power draws in a home, especially on the typical "lights" circuit most people plug their PCs into.

I'll by the fact that the PC is not the only load. Do you think this PC is actually using 1250W of power?? The power supply is only going to supply what it is aked for. The power supply failing has nothing to do with his "typical circuit" being overloaded. The power supply failing and consequently overloading the "typical circuit" had everything to do with the circuit being tripped.

[Jim Padgett 11]

Actually for an AC circuit.. power = voltage x current x power factor ....power factor is almost always less than 1 ... you may assume .9 or so ....So for 120 VAC x 10 amps x .9pf ... total power would be 1080 watts and I would be very surprised to see any home PC running that much power.Your loud pop could have been an electrolytic capacitor.... they have been known to explode .Power in must always = power out, so even though you have a 1200 watt ps it is not necessarily running at full load.To know for sure you must add up each load in your PC or use a power monitor to really find out.

[sluggy 3]

My job entails me constantly repairing 1.6kW PSUs (around 4 ft high) for a radar system. When a PSU goes 'bang' (and these do quite spectaularly, complete with mushroom cloud) it's usually when they suddenly come on load (only 40VDC out, with around 80-90 amps supply) and the FETs (big transistory things to the layman) get nice big holes in them and the plasma (yes, plasma) burns a 5mm deep hole in the heatsink mounts 2 cm away. Occasionally a cap will go, but usually something will break and cause the cap to go. At least that's my experience in high current applications.Cheers, SLuggy

[TechguyMaxC 516]

Great info sluggy! In my line of work I see MOSFETs fail on motherboards but rather infrequently compared to caps. Could be due to a difference in application, though.

[sluggy 3]

Heh, if your PC is drawing 80 amps it either won't be for very long ( :( ) or else it's a PC that will run FSX VERY nicely! :( Cheers, SLuggy