Is 550w psu enough?

[TheRadical1]

I recently built my first computer and it has the following specs:

Nvidia geforce gtx 760 gpu
intel i5 4670 cpu
asrock h87 performance motherboard
1 sata 3 hardrive
1 dvd/rw drive
1 regular 120 mm fan
3 led 120mm fans
ocz 550w fatal1ty powersupply

my computer is running and all but unexpectedly shut down a few times during games and i am just wondering whether i need a bigger powersupply or it is just a one off kinda thing that i shouldn't worry about?

 

[TheRadical1]

im pretty sure i put my computer together right and everything so if you know what could be causing it to shut down randomly it would be appreciated!

 

[Jameson Clark]

Shouldn't be the psu your system won't draw that much, but I couldn't give you a reason for the problem