PC turns on then off. Motherboard lights up and fans run

deadt33

Honorable
Feb 13, 2014
5
0
10,510
Just built it today and it ran fine for 5 minutes before it turned off and now I press the power and it just cuts out. Don't see anything that'd cause a short. I have
geforce gtx 970.
Msi gaming M5 motherboard.
16gb corsair vengeance.
i7-6700k 4.0.
H100i watercooling. 3 case fans. Powercool 850w psu.
The PSU is old and a bit dusty. I smelt something come from the pc (which obviously isn't good).. any solutionsuggestions I can do at home? Or recommend I take it into a shop and then replace the part that's faulty. Any help is greatly appreciated.