Power supply not turning on when connected to MB.

OGP4NDA

Honorable
Jun 15, 2012
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10,510
Hello, My power supply will not turn on when connected to the motherboard. the only thing that turns on is a green LED on the MB.

I built this PC about 5 years ago for a family member and its worked fine until a few days ago.

This began when the owner was playing a game and then PC shut off. I don't know what specific game but I highly doubt that my uncle was taxing the system too hard.

I did the paper clip test on the power supply and it failed. After buying a new, working PS (which passed the paper clip test) I am still having the same problem, after I connect the 24 pin main MB connector then the PS refuses to turn on, no fans, nothing. Just a little green light on MB.

I've reseated all components and the CMOS, tried different RAM configurations, and I dont see and bad spots on the MB.

Anyone know whats going on here?

edit* Motherboard is a ASUS M2N4-SLI
 
You mentioned that you plugged in the "24 pin main MB connector".

Did you also plug in the 4-pin ATX 12V CPU Power connector?

The little green LED that lit up on your motherboard just indicates that its receiving +5V standby power. The +5VSB is actually a separate linear power supply within the PSU that always remains powered when the PSU's main power switch is turned on.

Is the chassis power switch connected to the correct two System Panel Connector pins? You can remove the power switch lead and manually short the appropriate two pins on the motherboard momentarily to try and power up the system.

Have you checked for any bad capacitors on the motherboard?

What is the make and model of the replacement PSU?