Newish build now won't power on

[AggieDev]

I built a computer recently that now won't power on, even though it has run fine for the past 2 weeks I've had it. Now when I try to power on it simply doesn't boot whatsoever, though any USB peripherals that are plugged into the PC still light up. When I turn the rocker switch on the PSU off then on, when I first press the power button on the front of the computer I hear a very slight click and the USB peripherals turn off for about half a second then they turn back on. This happened first this morning when I was using the computer and it all of the sudden shut off. It was doing these symptoms and later in the day I tried turning it on again and it worked. Then this all happened again just now. What could be the issue? Here are my specs:

500W PSU
i5-3570k CPU
2x8GB RAM
GTX 760 GPU

 

[te100]

do you get any video? start by pulling all ram but 1 stick. unplug hd + dvd. If still nothing probably psu

 

[AggieDev]

I did the above and nothing was fixed, is there a way to test the PSU without unplugging all of the connections?

 

[te100]

well there is the paper clip trick but that only tests the switching circuit which could work but the psu will fail under load. No way to tell unless you have a tester. you can try to borrow a friends