Pop goes the PSU

  Aspman 11:56 05 Aug 2004

Just built a new computer for a client. Flipped the switch to power up and bang off goes the PSU.

IT was an Antec case with a 300W power supply. I'm a bit surprise that a good quality PSU went bang but no one is perfect.

I'm sitting with fingers crossed that nothing else in the case has been fried and I was thinking: is there a product that sits between the PSU and the other componants (mobo/CPU especially) to prevent a blown PSU cooking anything else?

I've got surge protected sockets connecting to the PC but obviously that won't help if a PSU is faulty. Would a circuit breaker help?

  CurlyWhirly 12:03 05 Aug 2004


Perhaps 300w doesn't produce enough power especially with the latest Nvidia graphics cards?
Are you by any chance using a Nvidia card?
I run a 430w PSU which is okay for now but I may have to consider upgrading in the future as I don't want to risk overloading it!

  Aspman 12:16 05 Aug 2004

No its a very basic system.

Athlon 2500+ with OEM fan and cooler.
Asus A7VX8-MX-SE onboard sound and video.
Lg 52x CDRW
56K modem.

Nothing else.

I'm not always convinced by talk of needing huge power supplies. I'd rather have a good quality 300W PSU than a cheap 500W.

We have 40+ basic Athlon 2500+ systems running on 275W power supplies and I've seen them run on 180W.

My own system has a 360W Cheiftec PSU and has
Athlon 3000+
Coolermaster Aero 7+
Geforce FX56000
USB powered ADSL modem
4x 80mm Fans
Fan controller
2x 80Gb HD

It's never missed a beat.

  myrtle the turtle 12:41 05 Aug 2004

I'm no expert, but most PSUs would have overcurrent and overvoltage protection circuitry on their outputs, so an underpowered unit shouldn't actually go 'pop'. However, if the PSU has failed completely, apparently noisily in your case, then it is possible that some damage might have been caused to the PC.

I don't know of any product that can be inserted between the PSU and motherboard to prevent this occurence, and in any case, such devices should be unnecessary with a properly regulated PSU.

You can only determine if the PC is OK by installing another PSU. If, for peace of mind, you would like to test that the power supply is operating correctly before installation, you could always stick a 6v or 12v headlamp bulb across the 5v output pins (because some PSUs require a minimum load to operate correctly), and measure the output voltages with a test meter, if you have one.

No doubt if the original PSU was faulty, there will be a disclaimer in the warranty absolving the manufacturer from liability for damage to other equipment!

  joelle1230 12:51 05 Aug 2004

a ups power supply could be the answer but cost a lot

  Tog 12:57 05 Aug 2004

You can buy PSU testers from some computer stores but they only carry out a very basic check i.e. they won't tell you if it's failing under a switching load.

No insult intended, but did you have the mains input voltage selector set correctly?

  CurlyWhirly 12:59 05 Aug 2004


I agree with you as regards buying a QUALITY power supply and I can say that I have a good make Enermax.
Well at least I think it is a good make - I sure hope so as it cost me nearly £80!

  Valvegrid 13:02 05 Aug 2004

The trouble is the semiconductor is the fastest fuse in the world, if you get a voltage spike form the PSU there's nothing that's going to stop the spike in time before it reaches the mobo. A circuit breaker is nowhere near fast enough.

Having said that, I think in this case its a problem with the switching transistors in the PSU in which case they have probably failed before anything reached the mobo, at least I hope so!

  €dstowe 13:16 05 Aug 2004

Ensure it was the PSU that was responsible for its own failure and not a short circuit on one of its outputs. The output from a PSU may be low voltage but it is very high current which can make quite a loud bang under fault conditions accompanied by a "wet" spark and considerable damage due to the high temperature achieved.

Do a thorough check of the all the things connected to the PSU before you even think about replacing it. (Fans, HDDs, optical drives, FDDs, motherboard, external connections to case lights etc.)


  woodchip 13:20 05 Aug 2004

If PSU goes there is no protection that I know of other than the Design of the other parts that will stop it doing other damage but all depends what blows in the PSU

  Aspman 13:45 05 Aug 2004

Thanks for all your replies.

I didn't think any sort of safety device existed but I thought it was worth asking.

I'm going to borrow a PSU from work tonight and test the remaining componants. I've had more than a few PSUs let go over the years and usually the rest has been ok, though not always.

I'll check out the connectors when I plug in the spare.

I don't know how I will stand if the PSU has damaged other componants. I was in a similar situation earlier this year where a faulty product had damaged my car. In that case I was entitled to claim the repair costs from the shop selling the product.

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