pc shuts off abruptly

Hello, since 3 days ago, I've been experiencing random reboots out of nowhere, no BSOD, no Warning, nothing. I checked eventviewer but as it restarts so fast it doesn't save anything there. I removes the battery and I'm now running only on the AC Adapter just in case it was a battery problem...

I built a new gaming computer a few weeks ago and have had very little issues with it. The first time I had issues was when I stupidly tried changing the RAMs voltage in the BIOS to a level that I thought they could handle but they failed. I rest the CMOS and my computer had very little issues...

I am really confused about What RAM i should go for. I am using MSI 970 gaming MB, nvidia gt730 2gb, AMD fx6300, cooler master fans, circle 500w smps. Now question is what RAM kite i need to go for, right now i have 8gb corsair vengeance DDR3 1600Mhz. As i heard itz not supported by MSI 970 MB...