PC hardware--CPU & Motherboard & RAM/System hardware problem, Inactive I/O


QUESTION: Hi Bobbert,

There is a problem with my desktop.
 System got shut down with a sound & the message "System shut down due to Thermal event overheating". I tried to start a couple of times, but it didn't start. So, I separated the processor from the heat-sink and applied "process cooling thermal paste".

Now the system runs but, I/O devices are not working (inactive). That is, monitor has no display (monitor light blinks), the keyboard's & the mouse's (optical) lights blinks for a split second and turns inactive. At this point, the CMOS battery is also replaced with the new one. Now even after repeated attempts to start the system, the problem still persists.

The system automatically gets power ON and runs directly when the system is connected to the power plug, even without pressing the power button on the CPU cabinet. The technician says, this should not happen.
The SMPS power plug (that connects the motherboard slot "PWR") turned dark a bit (like burn, only the plug).
The technician says there must be a problem with SMPS or the motherboard.

I couldn't able to find the actual problem.  
Kindly, guide me to the solution.


ANSWER: Any burn/singing marks is a very bad sign - it sounds like something has failed within the machine, and I'm inclined to agree with the technician that either the power supply or motherboard (potentially both) have failed and that's likely what contributed to the "thermal event" shutdown. It's possible that the CPU was also damaged/destroyed if the machine is only spinning up the fans (unless it's actually POSTing, it isn't technically running - spinning up the fans and disks just means they're getting power). My advice would be to pull the disks and salvage data from them, and move on to parts replacement (or, depending on the age of the system, total replacement if that is more economical). I'd start with the PSU if it has singe marks, and then move down the chain to the motherboard and CPU unless they're found to have singes/burns once you get the machine apart. Once the motherboard is replaced the operating system should be re-installed, and this is why I suggest salvaging/backing-up data before beginning repairs.


---------- FOLLOW-UP ----------

Singed SMPS plug
Singed SMPS plug  

Mother Board
Mother Board  

 Thank you for the answer & advice, you were spot on. You have minimized my doubt now, but I am reporting the present status of my computer. Wishing you would advice to this present status.
 Yes, there is a singe mark on the SMPS 4pin plug (connecting the motherboard).
 Suddenly system works & suddenly becomes inactive (only fans spin with the light on the motherboard ON). Even today, I could log in to Windows (after several attempts), and during working suddenly became inactive. System could once again starts working any moment (after attempts).
 I am attaching the pics, please have a look.

 This is my first ever computer, so I am very much intend to get it repaired & keep it working.

thanking you

The motherboard or other connected components were likely damaged by whatever event caused the surge/overload (which resulted in the singed plug). This is why you're experiencing erratic instability during operation. I would probably suggest backing up important data and replacing the system if possible - troubleshooting all of the various components will be time consuming, and if you have no other hardware it may be fairly expensive.


PC hardware--CPU & Motherboard & RAM

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I have nearly two decades of experience in IT, computer repair, and related fields and will attempt to provide the most solid, brand-agnostic advice when it comes time to purchase a new computer, or upgrade an existing machine. I can answer anything from the seemingly basic to the downright complicated - and will do my best to provide this information in a clear and concise manner.


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