Computer keeps blowing power supplies... Why?

[MarkS]

I built my niece a computer about 6 years ago. Over the past year, my sister has had to replace the power supply multiple times and is about to do so again. The computer works fine before the PSU blows. The house they live in is very old and the wiring is outdated and not up to code. Could faulty wiring cause this? What are some typical causes? My niece is severely autistic and uses the computer as an outlet. She cannot be without it for long, so this needs to be fixed promptly and completely.

[bdunham7]

Is your PSU a universal voltage input or do you have to select 115/230V?  Is it PFC?  Is it derated at least 50%?  What brand/model is it?  Does the computer have a powerful video card?

[wraper]

What PSU models were used? Have you ever measured mains voltage? I was repairing stuff at one remote location once in a while and they had repeated motor AC motor failures in certain type of device. Then I measured 280V mains voltage at certain time of the day. So I found that one of three phases their location was powered with often was wildly out of spec, switched stuff to sockets with different phase connected and no such failures since then.

[Foxxz]

Weak/old/dried caps on the motherboard may be causing additional load on the PSU

[amyk]

Definitely seems like bad power. The Repair forum here may help figure out what happened to the old ones, and even fix them.

[wraper]

Weak/old/dried caps on the motherboard may be causing additional load on the PSU

Nothing that could destroy PSU but keep motherboard working.

[Psi]

Sometimes you can be in a 230/240V country but the high voltage step down transformer is right outside your house and the power company has set the voltage tap a bit high because they need the transformer to reach a longer distance without dropping too low.

This was many many years ago, but It actually got so bad in some regions there was enough demand for lighting companies to start selling 250V incandescent residential lamps for the people in this situation because the normal ones you would buy at the local stores just couldn't handle 250 for very long.

[pickle9000]

Low incoming power from the wall. Electric heater, microwave or other high current device.

Plug a lamp in the same circuit use as usual and see if the lamp cuts out or flickers, then see if anything is doing the biz.

The outlet itself could also be having issues.

[Haenk]

Please add some bits of information.
Type of computer (maybe CPU, GFX, additional hardware - to estimate the load).
Type of PSU (manufacturer, model, wattage).
Wiring - AC or refrigirator running on the same wiring? Maybe install a line filter if there is massive line noise/spikes.

I just had it recently that a brand new PSU failed right out of the box. So that got replaced by a top tier PSU (at 150 EUR used it was not cheap though - but it will be used for years, on a daily basis, so no reason to cheap out...)

[AndyBeez]

Start by fitting an anti surge plug between the PC and the power socket. I would invest in a branded UPS with anti surge and power filtering. Price around $150 US.

One other question, is the ventilation of the PSU obstructed? Block the vent and the regulators will certainty fail.

[MarkS]

I forget this is a forum comprised mostly of engineers. Let me rephrase. Assume that the PSUs are high quality, name brand, consumer grade PSUs. Assume that, as such, the PSUs is not failing due to quality control issues. Also assume that the PSUs are designed for the North American market and are designed to run off of 110VAC @ 60Hz. I can only give the details of the PSU I bought to build this PC, but that was 6 years ago and has been swapped out several times since. I'll try to get the correct PSU info, but until I do, use the assumptions listed to come up with more generalized possible failure modes. I am not considering repair. Considering that this is happening with some regularity, and considering that the PC continues to function as designed after the PSU replacement, I feel it's safe to assume that the PC internals are not the issue.

[bdunham7]

I forget this is a forum comprised mostly of engineers. Let me rephrase. Assume that the PSUs are high quality, name brand, consumer grade PSUs. Assume that, as such, the PSUs is not failing due to quality control issues. Also assume that the PSUs are designed for the North American market and are designed to run off of 110VAC @ 60Hz. I can only give the details of the PSU I bought to build this PC, but that was 6 years ago and has been swapped out several times since. I'll try to get the correct PSU info, but until I do, use the assumptions listed to come up with more generalized possible failure modes. I am not considering repair. Considering that this is happening with some regularity, and considering that the PC continues to function as designed after the PSU replacement, I feel it's safe to assume that the PC internals are not the issue.

If all of your assumptions were true, you probably wouldn't have all that many failures.  There were good reasons that I asked the questions that I did, but I'll try and explain each of them.  I am not actually an engineer by trade and I'm speaking from some experience regarding failing PSUs.

First, the reason I asked whether these were PFC universal voltage units vs switched voltage selection is that one mode of wiring failure would involve shared neutral issues that can cause the voltage at an affected socket to go way up (or down).  If you have a PSU that is designed and rated for 85-264VAC 50/60Hz, this is unlikely to damage it, but if you have one with a 115/230 switch so that it is operating in a voltage-doubling mode, then 160-180VAC is going to be very bad for it.  BTDT.

The reason I asked about derating and if the computer has a power-hungry video card is that many consumer PC PSUs will not last very long if loaded anywhere near their ratings.  If we had some idea what the computer components are then we could figure out the maximum power required and you could tell us if the PSU is at least twice that--or not.

In my experience the most common causes of repeat PSU failure are low-quality PSUs and assuming that they will actually work at rated power.  There could be an issue with the house wiring, but if it were bad enough to damage a properly derated universal voltage PFC PSU then I would think that a lot of other things would be happening too.  The only other thing I can think of is that perhaps there are lightning surges and the socket that the PC is plugged into just happens to be extra vulnerable.  If it is a house wiring problem, a line-interactive UPS might help.

[pickle9000]

I forget this is a forum comprised mostly of engineers. Let me rephrase. Assume that the PSUs are high quality, name brand, consumer grade PSUs. Assume that, as such, the PSUs is not failing due to quality control issues. Also assume that the PSUs are designed for the North American market and are designed to run off of 110VAC @ 60Hz. I can only give the details of the PSU I bought to build this PC, but that was 6 years ago and has been swapped out several times since. I'll try to get the correct PSU info, but until I do, use the assumptions listed to come up with more generalized possible failure modes. I am not considering repair. Considering that this is happening with some regularity, and considering that the PC continues to function as designed after the PSU replacement, I feel it's safe to assume that the PC internals are not the issue.

If you look at my previous post, assuming the supply was good a low 110vac in can cause a failure. Switching regulators
don't like that situation. Because its infrequent plugging a standard led light in to the same 110v will flicker if this is the issue, this flicker
will also happen in the power supply and is an indication of potential power problem.

[J911]

If they keep blowing obviously it can't be the PS as they don't all know each other yet all suffer the same result. there is not much left but the AC at the wall or the remaining parts in the case, which would be motherboard or hdd. start by moving to another socket in the house with an etension cord. If you the problem continues its whatever is left in the case. probably a useless diagnose as it may take you months to find out.

[floobydust]

OP, some things to consider:

-I had cleaning staff plug (at work) in their vacuum cleaner same outlet (power strip, after the surge protectors) as the computer, and the spikes did damage, almost every weekend.
-The PC might have an airflow problem where the PSU fan cannot exhaust properly, if the case fan(s) also blow outward.
-The house might have a bad neutral in the service panel. This can cause overvoltage at the outlet. Usually shows up the worst when the stove is on high with smaller (120V) elements or any other high current 120VAC loads like room heaters, kitchen appliances, hair dryer etc.

You'd have to check what else your niece plugs in at that outlet or what else is on that branch circuit/breaker and see if it's making power surges.

[Mechatrommer]

I am not considering repair.

then why ask? buy new computer. (ps: you have nearly 1K posts that means you should be aware enough the culture of this forum)

[Haenk]

Assume

There is quite a benefit of getting older: I have learned to assume *nothing*.
Buy a new computer with on-site warranty, done.

[magic]

I am not considering repair.

I would consider an autopsy, though, if there are repeated paranormal failures there.

I feel it's safe to assume that the PC internals are not the issue.

They generally shouldn't be, except for cases of underrated PSU, insufficient cooling or dodgy PSU with missing overload protections.

[MarkS]

I am not considering repair.

then why ask? buy new computer. (ps: you have nearly 1K posts that means you should be aware enough the culture of this forum)

* the PSU. I'll repair the computer, but I'm not touching a PSU.

[Mechatrommer]

* the PSU. I'll repair the computer, but I'm not touching a PSU.

from my (our?) experience. the PC is a robust piece of equipment. we only need to do cleanup from dust from time to time. all my "cheap" PC is like 10+ yrs old and nothing wrong... 90% is PSU fault. if PC is the problem usually it wont turn on anymore even if using new PSU. if you really want to make sure, you'll need current clamp meter to see if PC consumes more current than it need to.. be ready with motherboard/cpu spec sheet. debugging motherboard is not easy anyway, many power rails need to be debugged, so...

and another advice, since your PSU keep failing, maybe its time to buy a hefty PSU 2x or 3x than its suppose to. maybe a 1000W PSU? being sick of regular PSU damage myself (cheap PSUs brand including few GigaByte brand that i thought to be ok) now i'm using china PSU meant for bitmining 2000W. now its a bit past 1 year in operation already so lets see how much longer it can survive. if it fail again, maybe i need to up the PSU price next time. i always (if i remember) to buy extra spare PSU early on because i'm too familiar with this problem, so i wont risk halted job later while waiting to buy new PSU. in fact just a few days ago i was hit by another SSD corruption issue, all OS dissapear! luckily i have spare (half capacity) SSD to recover backup OS into and i have spare PC to do the recovery process while waiting for a new full size SSD to arrive... cheap PSUs can work from only few weeks to few months.

as other advised as well, if you dont want to get into the mess, buy brand name PC with sweet promise warranty, Dell brand maybe? ymmv.

[paulca]

I had 2 instances of low grid voltage a year back.  (A local transformer had popped it's HV feed line, but because the network has multiple feeding lines for redundancy the others "back fed" the whole neighbour hood.... only they couldn't.  The engineer who fixed it said the transformer was steaming in the rain when they got to it.)

I had 195V when I should have had 240V.  The strange thing was, that almost nothing in the house "appeared" to notice.  Everything worked.  It was only when I turned on the microwave oven that my brow frowned as it sounded very, very unhealthy and on a quick test, did not even heat the food!

I figured I'd got away with it when they fixed it.

A week later I tried to use the washing machine.  Dead.  Luckily under "on-site warranty" they scammed me into paying for.  They came out 2 days later and ... ended up having to replace all 3 PSU boards in it.  The repair guy said it looked like it was bad power or a power spike, but the warranty was "hassle free", so still applied.

[Stray Electron]

My niece is severely autistic and uses the computer as an outlet. She cannot be without it for long, so this needs to be fixed promptly and completely.

   If you MUST have a reliable computer then go buy computer that is 100% made by Dell or one of the other good quality manufacturers. We have no idea what kind of bargain priced, low quality parts that you used when you built the computer or that your sister used when she replaced the PSU. And PRICE is not a measure of Quality so don't even start with that argument. There too many possibly software and hardware incompatibilities to deal with and too much poor quality hardware for anyone to troubleshoot it over the internet. Go buy a Dell or some other computer where all of the parts are known to work together as a system.

[Stray Electron]

I forget this is a forum comprised mostly of engineers. Let me rephrase. Assume that the PSUs are high quality, name brand, consumer grade PSUs. Assume that, as such, the PSUs is not failing due to quality control issues. Also assume that the PSUs are designed for the North American market and are designed to run off of 110VAC @ 60Hz. I can only give the details of the PSU I bought to build this PC, but that was 6 years ago and has been swapped out several times since. I'll try to get the correct PSU info, but until I do, use the assumptions listed to come up with more generalized possible failure modes. I am not considering repair. Considering that this is happening with some regularity, and considering that the PC continues to function as designed after the PSU replacement, I feel it's safe to assume that the PC internals are not the issue.

     Assuming is not troubleshooting!   If it was then we would just ASSUME that everything always worked and that all problems were due to operator error. 

[Mechatrommer]

Go buy a Dell or some other computer where all of the parts are known to work together as a system.

good brand motherboard such as Intel, or even more riskier but well known name such as Gigabyte or Asus can be a good starting point when DIYing PC system, read the spec sheet what cpu and ram it can takes and there should be very little can go wrong in like 7-15 years of usage. dont ever think of inventing new combination that is not in the spec sheet recommendation. "google-master" will also search for bug/damage/downside/flaw of each brand model before buying to get more bulletproof/guaranteed custom made pc system. the downside is finding good PSU for the setup. brand name PC dell or HP they usually have very good and robust PSU, but its very custom to their specific system that you cannot use it on DIY PC (standard ATX) the good thing is they last long, the bad thing is when they broke, you cant simply buy normal atx pc psu and put in there. you either have to order from authorized dealer and wait many weeks for it to arrive, or simply you buy new model pc of that brand, ymmv.

[nightfire]

What might add up to the mix: In grounded mains installations, such as the TN network used in Europe, you have the TN-C model which means that you have the phase/live wire and the combined "null" (Earth/Neutral) line.
The latter is the PEN wire. In this wiring, you have lots of stray currents travelling through a building via bridges such as metallic pipes, heating, etc. It is not uncommon that such things severely disturb IT Equipment.

I don't know what the situation is there with mains wiring, but something to keep in mind for future research.