I heard some strange noise from my less than a year old PC when it came back from 'sleep' mode; For about 10-20 seconds I could see bright light visible through ventilation holes (somewhere near the back panel); gradually the fire/flash died down, I could still smell some smoke out of it for the next 10 minutes afterwards. Upon opening up the case, I cannot quite tell where the burning exactly was coming from.

I had since turned it off and on several times, and had not noticed any obvious problems with it. Still all drives are showing, same amount of RAM, etc.

What component could have been burning like this? Will it do it again?

UPDATE: Thanks to all for the comments/answers: I have emailed the retailer (NCIX Canada) I got this PC from, with the description of the problem to see if their tech can take a look at it, as it sounds like I can't ignore it.

UPDATE 2: I had not tried everything indeed. Turns out the DVD drive connector cable was burned out; will see what happens now that both DVD drive and PSU got replaced ...

  • 1
    Where do you live? you may have consumer right, to a replacement. Jul 26, 2014 at 6:49
  • 3
    If there really is no loss of function (though you may not have discovered it yet), then it may be a noise related component. (noise being electrical noise, the device may start interfering with other equipment, or be susceptible to noise from other equipment) P.S don't inhale the smoke. Jul 26, 2014 at 6:52
  • 11
    Turn it off, and and get the local service center open it up and check. Even if it works now you want to work out what's wrong. There's quite a few things I can think of, none of which are good for your computer in the long run. Magic smoke escaping is NEVER good. In addition to caps, it may be a voltage regulator - 3 leaded device, often soldered or bolted to the board its on.
    – Journeyman Geek
    Jul 27, 2014 at 1:52
  • 7
    From the title, I assumed someone was building a parts list for the best computer ever.
    – phenry
    Jul 27, 2014 at 23:39
  • 6
    May I just add... the title of this question must go down in history as the funniest ever
    – Jodes
    Jul 28, 2014 at 10:45

8 Answers 8


A burning capacitor could be your culprit. Regardless, if you saw a flash, or fire and noticed any smoke, the fact you've not noticed any problems simply means you've not yet tried to use whatever is broken. There isn't anything inside your computer that will keep on working happily after burning up. You should open up the computer and see what's been damaged. If you don't address the problem while things are working, you may have a small problem turn into a bigger and more expensive problem.

Good luck!

  • A cap blowing wouldn't produce any more light than a brief flash.
    – phemmer
    Jul 26, 2014 at 17:47
  • 7
    I had a large PSU cap blow (completly pop open with a loud bang) , and subsuqent fire existed that was not arcing. The fire burned what looked like the paper of the capacitor guts, for about 7 seconds, visable flames showing out the back of the PSU. Nothing other than a capacitor was visably damaged. The High voltage cap blown out would not fully stop the PSU from operating, but I certannly was not going to leave it that way, nor was I thrilled with the quality of what was a $200+ Psu of an overhyped brand name. It also would stink for a long time. I just replaced the whole PSU.
    – Psycogeek
    Jul 26, 2014 at 23:49
  • 4
    I'd like to know the brand name...?
    – Dean
    Jul 28, 2014 at 6:22
  • Full PSU burnout works quite close to flashbang. Its hard to find video of it as it requires spontaneous failure of whole PSU in right way, but this one gets close to how it looks. Full failure will compress light into one flash, left me blinded for minute or so, and it was from few meters and through vents, but I was looking directly at it at that time.
    – PTwr
    Jul 28, 2014 at 7:48
  • Stop right there, friend, for a moment. Think how your answer is an improvement over answers above. A burning capacitor has already been mentioned and the answer is voted up as well, how is your answer better than that? Please read this.
    – user260419
    Aug 12, 2014 at 13:49

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Almost certainly a Capacitor.

This happened to a Dell server that was running under my bed (don't ask, but basically to reduce the noise in my room) and didn't have enough ventilation.

Usually the area of the cap burst has smoke residue around it and in my case there was a strong smell associated with the burst and a 'pop' sound.

Server however kept on going....

  • 12
    Good hardware will continue to work, however you may begin to notice general system instability. I had a motherboard that bulged and blew a number of caps, but still worked fine. As time went on, I kept getting more BSODs, hard drives failed to recognize, and various other strangeness. Replacing the motherboard cured all issues. Jul 26, 2014 at 16:58
  • Doesn't even need to be good hardware - I had a cheap desktop machine whose motherboard was populated with capacitors produced by one of the manufacturers involved in the "badcaps" issue. When it eventually failed, I checked the board for blown caps and found 7 of them. Apparently it had continued working despite the first 6 failures...
    – Jules
    Jul 28, 2014 at 4:37

I would bet a bug or other pest crawled into your power supply and was at the wrong place at the wrong time.

Open it up, if you have scorch marks on your motherboard, back up your data and replace your motherboard.

Otherwise, I'd replace your power supply as a precaution.

EDIT: Back up your data anyways. Also, do not open the power supply to check. If you notice nothing burnt/scorched with your motherboard or any other component in the system, replace the power supply.

  • 3
    Agreed for the fact power supplies are a common source of smoke smell when they fail. If the OP doesn't find any visible signs of damage when inspecting the inside of the PC, it would be safe to assume the P/S was the culprit. Jul 26, 2014 at 5:17

The most likely culprit is a capacitor. Every part has a reason to be there; no part can fail without some adverse consequence on the system's operation (even if it's not immediately apparent). If the system appears to be working OK, then (total speculation) it might be a power supply filter capacitor on the mother board. Electrolytic capacitors are notorious for having very finite operational lifetimes. Of all components used in a computer (and computers contain lots of them), an electrolytic capacitor is most likely to be the first part to fail. These devices are also notorious for going up in a puff of smoke when they do fail.

Power supply filtering (one possible application of a capacitor) is intended to smooth out the voltage on the power bus. Without it, there will be more noise and voltage dips/spikes on the bus than with it. This is generally not a good thing because it can increase voltage stresses leading to failure of other parts, and at the very least can make the system unstable - prone to random glitchy behaviour of programs or the system as a whole. Although a filter capacitor could fail any time the computer is in operation, the most likely time it would occur is when the system is powered up, due to associated inrush currents and voltage surges. Although it could be located in the power supply, the fact it was so visible to you, and that it didn't have any immediate apparent impact on operation suggests that the failed part was likely on the motherboard. The capacitors in the power supply are usually much larger, and a failure of one of those would be more likely to produce an immediate, noticeable effect - the power supply going totally inoperative or the system being unable to start up on the degraded power.

Any evidence of smoke/fire should be followed up by careful inspection and checkout to identify and repair/replace the failed part. Continued use of the damaged and unrepaired system would not be a good idea.


On top of what Twisty and ultrasawblade raised, some cases are not designed well (or not well made), and may inadvertently place sources of heat (CPU, GPU etc) too close to material that melts or may burn.

Same idea as what others have said, open the case up, and if you see any discoloured or disfigured parts then try and determine what could cause it.

In my case, I had a side fan, with a cable that draped over the Graphics card when the case was shut. One hot summer day I noticed a burning smell when playing games, and the cable had melted partially. I tied it up properly and never had the issue again.


Well another issue is that it increases the likelihood of a future fire or data loss. The power supply for example could take out the HDD and MB when it finally dies. Computer power supplies usually have almost no fire protection compared to say, the setup in an automobile or your household wiring.


My previous computer was on nearly continuously. It turned out my Media Center PC had over heated and the capacitors were bulging all over (the electrolytic kind.) Needless to say my replacement computer was designed with 2 ideas in mind, solid components (that would be harder to stress) but more importantly, a non-manufacturer model specific case so that the aor flow would be far more effective. I have only had this computer for 3 years but it seems to be doing well so far, I probably went overkill with solid component motherboard. But as far as cooling goes, while I may have overkilled it, it certainly is not as awful as what was in that media center PC. crammed in a case and small opening ans well as fans.


Its power supply unit. You should really replace it and not use the computer until you do it.

  • 1
    "You should really replace it and not use the computer until you do it." - Agreed. "Its power supply unit." - hard to tell, it could be anything.
    – gronostaj
    Jul 27, 2014 at 22:35

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