Computer shut down, without any reason

Inolution

New Member
I built my desktop pc about 6 months ago and it has been amazing to use and play games on. Today when i came home from school and wanted to go on and use my computer it all worked fine, i watched a youtube video and then went on steam to play some games.
Then my computer just shut off. I then opened it and cleaned everything but nothing works or responds, i can't do anything with it too get a response. Please help.
BTW. I checked my computer afterwarss top see if it was a heating issue and every single part was cool.

My pc specs are:
Intel core i5 4690k, gtx 970 g1 gaming overclocked, 750w coolermaster bronze power supply, 8 GB ram, Asus maximus ranger motherboard, seagate hdd.
 
Top