Is 520W PSU enough?

I changed a few things in the build and i want to make sure this PSU will run it all.

PSU

Motherboard
RAM
GPU
CPU
Case(dont think this affects is but incase it does)
HDD

The DVD/CD drive, im just going to keep an old one i got somewhere is the house its one of the old ones that used the IDE pin connector not sure if this will make a difference.

you'll be fine...says herehttp://www.guru3d.com/article/radeon-hd-6850-6870-review/10 that it pulls 295w at FULL stress

here ya go bro, you just saved $20

http://www.ncix.com/products/index.php?sku=56262&vpn=HD687AZNFC&manufacture=XFX&promoid=1359