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February 7th, 2025 16:52
Dell OptiPlex 755 MT - Random Power Cut + Concerning Burnt Smell
Hello Dell Community,
I hope everyone is doing well today. I have a very worrying issue that has just cropped up that involves my Dell OptiPlex 755 MT. The system will randomly cut off power and the Power Button LED will start blinking and is unresponsive. This issue happened before on 25th May 2024, but it was able to recover after turning off power from the wall outlet and turning it back on again.
Fast forward to 7th February 2025, and the issue has come back but this time, the system smelt like something was either burning or something was burnt. When I noticed this, I immediately cut power to the system from the wall outlet and investigated carefully to see if a capacitor had burst. I couldn't see anything, but old Dell Forum Threads did say that the power supply might be faulty. Could you please help me figure this out and what the best course of action is? Thank you.
redxps630
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February 8th, 2025 01:05
it may not be worth the health risk to try diagnose and repair this model, unless you have a strong sentimental attachment to this unit. If not, e-cycle it and move on to other interesting computer project is what I would consider
redxps630
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February 7th, 2025 17:34
it may or may not be psu burning. I have seen old optiplex mobo burn w plastic smell too. if you have a spare 24/4 working psu you can use it to test mobo. if mobo is still safe and okay to use, replace cmos battery w a new one and clear cmos settings by mobo RTCRST jumper
MasterTechnology507
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February 7th, 2025 22:32
@redxps630 I see, I don’t have a spare power supply to install in my system. I also don’t know if my system is safe to use after today. I had a random shut down occur on the PC in May 2024 and it didn’t smell off then. But when it happened again on 7th February 2025, that’s where I felt something was really wrong with my PC.
MasterTechnology507
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February 8th, 2025 18:33
@redxps630 I see, if you don't think it's worth trying to track down a new power supply for the system. It might be safer to strip it down and scrap it. The system is almost 17 years old so I can see what you mean by it's not worth the health risk. As for a replacement system, what would you recommend as a PC that can run Windows XP and Windows Vista? Would acquiring another Dell OptiPlex 755 be worth it or would it be risky considering the power supply failure that has been occurring on my particular unit?
redxps630
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February 8th, 2025 18:36
get a Optiplex 790 MT which supports XP and vista
https://www.dell.com/support/product-details/en-us/product/optiplex-790/drivers
much easier to repair if a component needs replacement
it is standard mATX using ATX psu
MasterTechnology507
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February 9th, 2025 11:59
@redxps630 Thank you for your advice and suggestions. I really appreciate your time helping me with this. I will go forward into looking for a replacement PC for use in Windows XP and Vista. 😊