Question can i use 320w power S for my GPU which require 400w

[mzmshah]

so i am planning to buy hd 7870 graphic card which require 400w power supply but i have power supply of 320w will it run it or not.
my spec
CPU: i5 650
ram: 8 gb
psu: 320 w from hp company (dont know its model)

 

[DSzymborski]

If you can't find a model, you need to upload an image of the PSU's label to imgur (or any similar photo-hosting site).