Computer shutting down after installing new GPU, not over heating

[purplefetus]

I recently upgraded my GPU from a 660 to a 780 ti. It goes fine until I try to play a more graphically demanding game then it just shuts off. I monitored my heat levels and those were all fine.

 

[popatim]

System specs including the PSU plz

 

[purplefetus]

System specs including the PSU plz

780 ti
i7 3820
525w psu
windows 7

Not sure on the psu, on the end of the cable it says 1250w?