Gaming PC Crashing

[Woodie2012]

Hi so i have had my gaming pc for 3 month now i have had no problems with it but today it has crashed 3 times it does not bluescreen it just stops i can't CTRL+ALT+DEL or anything. i can't figure out why i have a duel monitor setup i play my game on one screen and watch livestream on the other when my computer crashes using speedfan my gpu is at 50c and my cpu is running at around 60% so i am really stuck any help would be much appreciated thanks.

My PC specifications
AMD FX-6 6100 Black Edition 6 Core 3.3Ghz
Sapphire HD 7850 2GB GDDR5
Gigabyte GA-970A-DS3 Socket AM3+
Powercool 750W Modular PSU
Kingston 120GB HyperX 3K SSD 2.5
Antec Kuhler H2O 620 Liquid Cooling CPU Cooler
Creative Sound Blaster Audigy SE 7.1 Soundcard

 

[ATMINSIDE]

Run Memtest86+ and Chkdsk and let us know the results.