Unexpected Shutdowns Please Help!!

[Soulx]

Unexpected shutdowns doing the basic tasks on my pc.

System:
i5 3570k @ 4.0ghz w/ CM Hyper 212+
P8Z77-VPRO
16gb ram
HX 750W
600T
Samsung 840 250gb
EVGA GTX 760 (Newly installed 2 days ago... Upgrade from hd 6870).

Played battlefield 4 for a solid hour last night and it didn't turn off till I was watching a video with amazon unbox. Then today it shut off while watching a youtube video.

I checked the temperatures from hw monitor and gpuz

Temperatures from the processor average around 30C
the graphics card around 28C. 
Motherboard around 32C.

It doesn't make any sense if it was the gpu, I mean why would it work flawlessly on a gpu intensive game like bf4 and then crash doing something so simple as watching a youtube video.

Please help!

 

 

Key things to note: I had a gtx 770 but I had to return it due to bad memory & the fact that I spent too much money. 

I also posted on tomshardware, they came to the conclusion that my motherboard has power issues or my power supply has issues as well.  

This is a pic of the errors that I get http://tinypic.com/view.php?pic=1h8lls&s=5#.UsiHcWRDtst all of them are the same error.  

[TechSage]

Are you sure the OC is stable?

[Altecice]

Does it hard lock when watching YT videos or does it actually shut down?

[Soulx]

Haven't had any issues with my oc.  The shutdowns occurred after I installed the gtx 760, as I said above that worked flawlessly when playing bf4.  It's been two days now & I've taken my 760 out & put my 6870 back in and there hasn't been any shutdowns since.  

 

As for the shutdowns it acts like the power goes out and it has a hard shut down, one time I was able to turn it back on immediately the other time it took a few seconds for it to turn on again ( like I pressed the on button several times and it wouldn't turn on ).