Having some issues with my PC. Fans and lights go for a split second then shuts off. Tried the paper clip test with the cpu and the dummy adapter evga included with the supply and it didn't even make the fan spin.

What's odd is the PC was working fine this after noon but the previous night I left it on over night for around 15 hours on lock mode and got back on it for a bit in the afternoon around 3pm and shut it off around 630pm like normal to run errands came home tried to turn it on and it never came back on this morning

I've tried everything Mr.T gave as advice on the discord and even took the risk and tried it on a completely different old system with its own gpu, Mobo, cpu and it did the exact same thing. Lights, fans spin off.

The power supply is a evga supernova 750b the only other thing of note is that it's 4, 5 years old.

Am I correct to assume it is the power supply?

Hey hifi,
If you have a multimeter you could test your power supply but it does sound like that is the cause. Not sure if you still have original invoice etc from when you bought it but evga do a 10 year warranty on some of their power supply’s worth looking into

It sounds to me that it is the PS.