Sounds to me like your motherboard has issues. Check what your 12v and 5v readings are.

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Take out the cmos battery then unplug the 24pin atx and 4/8 cable and take a qtip, remove about half of the cotton then apply some isopropyl and get it gently between every pin in the 24 atx and 4/8 slot. I have had issues like this and it turned out my 4 pin slot was dirty. If I wiggle a few wires on the 24pin while my pc is on my 12v and 5v either go up or down but I have my reasons to leave it like that.

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You might be using a usb device at times that damages your ports or shorts them out i’ve had issues like that.

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Lastly you could have a bent pin in the cpu socket

Sounds to me like your motherboard has issues. Check what your 12v and 5v readings are.

​

Take out the cmos battery then unplug the 24pin atx and 4/8 cable and take a qtip, remove about half of the cotton then apply some isopropyl and get it gently between every pin in the 24 atx and 4/8 slot. I have had issues like this and it turned out my 4 pin slot was dirty. If I wiggle a few wires on the 24pin while my pc is on my 12v and 5v either go up or down but I have my reasons to leave it like that.

​

You might be using a usb device at times that damages your ports or shorts them out i’ve had issues like that.

​

Lastly you could have a bent pin in the cpu socket