Computer freezes during video converting

Hello all,

I am running a custom built tower built by me. Specs:
-windows 10
-amd vishera 8 core 4.7 ghz processor (been overclocked automatically to 5.1ghz)
-asus mobo
-900w bronze certified psu
-2gb xfx 7970 graphics card
-160gb intell ssd to boot from
-other hdd for storage
-16gb of kingston RAM

My computer keeps freezing just after starting to convert a video to mp4 so I can put it into iTunes to use apple TV. I have tried multiple converters and they all do they same thing. I could convert no problem before. This is issue has been ongoing while I was still using windows 7.

Any help will be greatly appreciated.
Thanks