Brand new built PC randomly turned off after 8 hours of use and won't turn back on

[Mopar24]

Just built this PC

I5 6500
Gigabyte Z170-HD3 motherboard
Ripjaws 2x4 ram
Gtx 970
Kingston SSD 120gb
Evga Gs 650w power supply
Thermal take g41 case

I was playing about 8 hours after building it. Each core of the processor was not above 25 degrees 2 hours before it shut off. It was a random shut off no blue screen nothing. Thought maybe it overheated waited 30 minutes to turn it back on then the fans spun leds on the fans and motherboard came on then instantly turned off. An hour later same deal and many hours later still the same. No friends want to let me use their power supply so I can't test it and the Gs has all black wires so I can't test the power supply it self. I'm thinking it was the power supply because I took a gamble and bought a refurbished PSU. I've called to RMA it and have the new one on its way but I'm just curious if that's really what it could be. I'm a mechanic and my automotive instinct is telling me that if the motherboard was fried none of the fans or leds would work but I'm not a tech guru. Just hoping for some peace of mind that it is the power supply and not one of the brand new components and I have to wait even longer. Thanks In advance.

 

[alexoiu]

You can test the power supply: http://cdn.overclock.net/d/da/da87333a_ATX24-1.jpeg
The test is relevant only if a fan connected to the power supply does not spin.

 

[Mopar24]

All wiring to the PSU is black but if it's in the same location I could bridge it with a paper clip and test to see if it spins.

 

[Mopar24]

Well the PSU fan spins. One time it got a little weird and wouldn't turn back on but I switched the ground and it turned on. So now I'm even more confused.

 

[alexoiu]

It could be a power button issue. Try starting the board by shortly touching with a screwdriver the 2 pins on the motherboard corresponding to the case power button.

 

[Mopar24]

The papeclip doesn't put any load on the PSU and since its refurbished any number of the cables could be faulty. The new power supply comes either tomorrow or the next day and ill plug it in and see if the problem is still there

 

[alexoiu]

ok.