Computer won't switch on and has smoking PSU

  Charence 16:27 11 Dec 2004

I've just built a new computer and it has been running without problems for a few days (exc. LED problem). Yesterday, I was installing my ADSL modem software on the computer before it suddenly switched itself off. Upon restart, my USB devices kept switching on and off and around 30minutes later, the computer once again switched off.

When I switched it on again, nothing was displayed (BIOS etc.), the keyboard was not responding, the monitor reported there was NO SIGNAL and the only thing which seemed to work was the CPU fan, and the USB mouse which was being supplied power.

Assuming it was the PSU, I swapped it with a similar 300Watt on another computer and when plugging that in, there was a faint whirring noise but the motherboard power LED did not light up. I tried switching on the power of PSU again, and smoke started coming out of the PSU.

I have no idea of what could be wrong. The PSU which was originally on the new computer is new and has 300W output.

Any ideas much appreciated.

Thank you,


  woodchip 16:40 11 Dec 2004

you need a New PSU with more power. I.E. 550watt

  mattyc_92 16:41 11 Dec 2004

When building the system, static may have charged and damaged the components..... Best bet is to take it apart and start again, making sure you "ground" yourself!!!!

  Noelg23 16:43 11 Dec 2004

failing all that u will need to rebuild with new parts...

  Charence 16:46 11 Dec 2004

Are you being serious? All I'm going to run from it is 1x 120GB HDD, PIII 1.1GHz, 512MB SDRAM, CD-RW, Floppy, USB Modem, USB Mouse and a USB hub which will be self powered. What do you think, is my PSU too small?

The new PSU which isn't smoking does smell a bit and has problems booting up system, so shall I send that back to eBuyer because I only received it on Monday?

I'll try to reassemble the PC.

"Ground yourself" - does touching the metal panel count? That's what the instructions say, or do I need something else to ground myself?



  mattyc_92 16:52 11 Dec 2004

Doesn't really matter, as long as you touch something that can conduct electricity (other than the computer)

  Gongoozler 16:52 11 Dec 2004

Rebuild with a new power supply, they are available at a very reasonable price starting at about £13 click here. Initially fit only a minimum of components, motherboard, processor and heatsink, power switch and case speaker. Be careful that nothing is shorting to the case, even to the extent of placing the motherboard on a sheet of card. You should then get a BIOS error beep because you don't yet have any memory or graphics card. If this works, you can then start adding components.

  ACOLYTE 16:56 11 Dec 2004

550 is extreme for your pc i would say 350/400 would run your pc good enough as for grounding yourself when you change the psu,just touch the case to get rid of static and then swop psu unit should be easy enough.

  Valvegrid 17:00 11 Dec 2004

It sounds as if something is shorting. First thing is to remove ALL the peripheral cards and other devices that rely on power from the PSU including the drives. Then switch on and see if the motherboard powers up, if it does, you're in luck, if not then it maybe the PSU or MoBo, you may need a bit more technical help from someone who knows how to fault find. If it does power up, start adding the devices one at a time till you find the culprit.

Yes, using the frame of the computer is acceptable, this will make sure any potential difference will be the same on the card, as it will on the computer. Modern cards are pretty tough, I have abused them at work and never had one die from static yet, but it is best to take precautions anyway.

  Charence 17:03 11 Dec 2004

I'm not sure if I'm plugging in the system panel connector correctly. The plugs have some arrows on them. Currently I'm plugging in the arrows into the positive pins, I'm assuming this is correct because the case didn't come with a manual. Am I correct?

  Gongoozler 17:03 11 Dec 2004

New power supplies always smell a bit and failure to boot isn't necessarily a power supply problem. A PIII 1.1GHz should be OK on a 300W supply, but is this really a new computer with this age of processor, or do some of the parts have an unknown history?

Antistatic precautions are mostly a matter of common sense, but if you want to be really sure, wire up the computer to a mains plug with only the earth cable connected (the line and neutral wires carefully tied back and their pins left out of the plug). You can then be sure that the case is grounded with no risk of power being applied, and you can ground yourself to the case.

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