Need help guys: PC turning on for a few seconds, fans start running, etc, then shuts down and repeats

So yea, this started happening a couple weeks ago, but it's gotten to the point I cannot use my pc anymore at all. Initially it would do this cycle, but then eventually sort of "kick in" and run normally, but not its just a constant bootloop.

When powering my pc on everything will turn on; fans, cpu lights, cpu fan, etc, but then after about 3 seconds will just turn off and go through the same process, without me touching the power or anything.

Ive read that this could be a few things. I will note I was getting a low ram warning prior which isnt normal for me because I was just using chrome and league, so I'm thinking that the ram could have went and seen other cases where that was the problem. I tried taking the ram out and putting them in one by one in different slots though and still cannot get it to boot.

This is my first custom built pc I had it for about a year and a half and this is my first real issue so I could use the help of some experts.

its

i7-4790k gigabite windforce 970 EVGA SuperNOVA NEX750B 750 WATT Bronze Gigabyte GA-Z97X-SLI 2x 4g hyper fury x ram ddr3

Heres a youtube video that looks like whats happening on my rig. (its not my video, but gives you an idea)

https://youtu.be/bWACghs0oQA

Anyone have any ideas?

edit: as im writing this it powered on. It was bootlooping like that for over an hour, I did nothing except let it keep bootlooping and than it just worked. Any ideas on what I can check now that it's powered up?