Psu suddenly stopped working

Jan 3, 2019
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Hi guys, I have a noob question to ask. I'm currently in the middle of building my first DIY pc, and wanted to do a power on test on my psu last night... EVGA Supernova G3 750w. I connected up my 4 casing fans and started up the power. Everything ran fine, fans were turning on the psu and casing, LEDs lighting up. I turned the main switch off and went to bed. This morning I tried to power up the system again and nothing works. I confirmed there's power from the cable and the switch is on, so what could the problem be? I find it quite difficult to believe a brand new psu could just die overnight like that.

Edit: forgot to mention, I didn't connect up anything else to the psu other than the casing fans.
 

darkbreeze

Titan
Moderator
How did you "connect up the casing fans" if you didn't connect anything else? Unless you were using Molex adapters to power those fans you'd have HAD to connect the PSU to the motherboard, and had a CPU installed, or nothing would have even tried to spin up. This is exactly why we tell people over and over again to bench test the whole system before installing it in the case AND to have EVERYTHING installed including the CPU, memory, CPU cooler and motherboard before ever powering anything on.

How are you turning on the power supply? Is it connected to a motherboard? Is the motherboard connected to the case front panel connections?
 
Jan 3, 2019
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Oh, yes those were Molex fan connectors I was using. So no motherboard connection was used there.

The power supply is connected to the wall socket, and I'm turning it on using the switch on the back. The motherboard isn't connected yet. I thought I'd like to verify the psu is working properly before connecting up to anything sensitive.

Edit: typo
 

darkbreeze

Titan
Moderator
The switch on the back does not "turn on" the power supply. You need to trigger the PSU on by either connecting it to a motherboard that is connected to the case "On" switch, or by using a paperclip to trigger the PSU on as seen here:

https://www.youtube.com/watch?v=ixcWCrYpw3Y


All the switch on the back does is make power available to the switching circuit. Without being switched on and seeing the power good signal, it won't supply power to any of the rails. You can override this using the paper clip method but honestly I would advise that it is not only pointless to do so, it's also usually a poor idea to power on the unit without it being connected to a functional system so that it's full protections are operational.
 
Jan 3, 2019
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Thank you, I realized the psu did come with a test socket which fits into the motherboard connectors, and this was connected last night when I did the first test.... Then I foolishly removed it before going to bed and forgot about it. That should be the cause then, thank you for pointing that out.
 

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