Sufficient PSU for rig?

[nudd]

Currently have a seasonic 620w.

Powering an i7 2600k, haven't bothered to OC. 16GB ddr3 1600 ram, and currently a crossfire 6850 setup. My question is, will this PSU be enough to power the upcoming GTX 680? Probably going to look into buying one of these in the near future when they are released. Once again thank you guys for your time!

 

[nudd]

Also... my mobo only support PCI-E 2.0. Would it even be worth it to upgrade?