Computer loses all power for a second then restarts

Hi, I am kind of new here but I have been having a very irksome issue. :cry:

Several months ago I have built my first new computer. Everything was working perfectly. Now for some reason, about once every 24-48 hours, my computer randomly shuts off (not safely, as if I took out the power source) and restarts itself.

I am sure that it is not a temperature issue because this happens when I am just watching some YouTube videos.
If it helps, I have noticed this issue started ever since Hurricane Sandy hit my area and Con Edison forcefully shut off all power while my computer was still on.

My hardware:
Crucial M4 SSD 64GB
Gigabyte gtx 670
ASRock Z77 Extreme4 1155
Intel Core I5 3570k

I appreciate any help or advice given.
Thank you!

TL;DR: computer shuts off instantly from time to time on an inconsistent basis and restarts itself