My motherboard got fried!! What could have happened?

Recently one of my friend's system got damaged.....We were using the system and suddenly there was a powercut........then there was a sound from CPU. On opening it we saw that the mother board n all its components were burnt... What actually must hav happened?.. Some say its due to voltage fluctuations .......some say it was short circuited........What actually happens when voltage fluctuates?......(the system was also earthed.......people say earthing saves the appliances from voltage fluctuations but i wonder what could have happened.) Can someone please give an explanation?

purifier said:

Recently one of my friend's system got damaged.....We were using the system and suddenly there was a powercut........then there was a sound from CPU. On opening it we saw that the mother board n all its components were burnt... What actually must hav happened?.. Some say its due to voltage fluctuations .......some say it was short circuited........What actually happens when voltage fluctuates?......(the system was also earthed.......people say earthing saves the appliances from voltage fluctuations but i wonder what could have happened.) Can someone please give an explanation?

Click to expand...

Probably the case of bad quality ATX power supply unit inside that computer, especially bad is JNC brand (Made in China). It was certainly caused by mains voltage fluctuation, probably some power surge came in through the power grid, but in case of good ATX power supply, it should not cause any damage to motherboard. Regarding earthing, its primary function is to save user/operator of an electronic device, in case something bad happens inside the device and mains voltage appears on the metal case.

Thank you... Yeah even I was wondering.. What could have happened so terribly that could burn out the insides of the motherboard...

The computer CPU is powered via SMPS which is not isolated from the supply line.

A large voltage spike fried the electronics...

Ican bet you don't have a UPS.. na dif you do, it's an online, low switch speed one.

I am so sorry your CPU got fried..

I hope this answer helped you ?

Yeah he does not have a UPS Thanks for the answer..

purifier said:

Thank you... Yeah even I was wondering.. What could have happened so terribly that could burn out the insides of the motherboard...

Click to expand...

Trust me, I saw some cases of ATX (already mentioned JNC brand) malfunction, due to bad construction/layout of the parts, leading to 1µF capacitors in primary circuitry to dry out, causing total malfunction of ATX PSU, letting for instance up to +10V out instead of +5V, causing total destruction of almost all components inside PC.

The latest breed of extremely lightweight SMPS are frightening... I look at most of them out of curiosity...

They are minimalistic - in theory the designs are actually very good, but in practise, they are deadly... most of the components are HEAVILY underated !

This was the answer I got when I tried to explain him what could have gone wrong...


Well, I just got confused when he said his SMPS was working fine. A few days back I heard that even the internet cable can be responsible and so I told him that for which he gave me the following reply:

"I was connected to the internet - LAN, Motherboard, Spikegaurd got damaged. If it was due to internet cable, how can the spikeguard get damaged. Why didn't the SMPS get damaged? Even that is in the same path"

Any clues?

Power surges are one of the most feared incidents on electronic devices. Same as a computer, they are really susceptible to power surges. Even though surges usually last only milliseconds (and are somewhat filtered by the transformer in the power supply), that high voltage can exceed the withstanded voltage of the insulating layers inside the integrated circuit chips and burn everything inside your computer.

The power delivered to your electronics devices and computer is stable and constant, in theory of course. In real life, it doesn't work that way. Often power surge occurs when the normal flow of electricity is interrupted, and then started again, or there was an occurrence that something sends excess electrical energy into the system. Any number of events, from lightning strikes to power failures, can cause power surges. Even your own electrical devices and computer can cause them. Refrigerators and air conditioners, for example, have motors that turn on and off, diverting electricity to and from other appliances and producing low-level power surges. On computer, internal peripheral can cause small surges that can reduced your computer lifespan or even destroy it completely.

Can someone give an answer for my question?

BTW thanks lmtalsoul...but my doubt is still hovering in my mind...

purifier said:

Can someone give an answer for my question?

BTW thanks lmtalsoul...but my doubt is still hovering in my mind...

Click to expand...

If there was some thunderstorm going on at that moment then it could explain the damage caused by other source than power fluctuation. But usually ATX power supply suffers damage as well. Then again, in case of lightining, one newer know the path of electrical current in that case. I had the case of fried computer, phone and answering machine (PC was off /mechanical switch, it was ancient PC XT/, but modem was plugged in, answering machine was pluged in power) and TV that remained intact and was on at the moment when lighting stroke neighboring building. So in such cases you really newer know what will get fried and what will stay alive. Another posible scenarion in your frined's case is if the phone line through which he is connected to the net is not underground, and if there are some power lines nearby, it could have been the case of "flashover" between the lines.

Thanks a lot... I'm convinced... I'll try to convince him too...