GIGABYTE GV-R927XOC-2GD

I have a friend to take the AMD r9 270 GIGABYTE GV-R927XOC-2GD
It will take a new graphics card with the processor, and I deshovke sells old, has already agreed to give the test, and so on.
Here is the problem, it is recommended that 500 watts on the PSU, and I have it on 450 watts, that's asking a question, will this problem or not?
Thanks in advance!