I would not recommend a 650watt PSU for that. It technically would be enough but you would be cutting it very close to the limit and you don't want that. PSU's in my opinion should always be a little overkill for their system just to be on the safe side as your entire computer's life literally lies in its hands. I would say a 700watt minimum and I'd recommend a 750watt if possible.
I took a look at several competent technical reviews. Results varied based on system configuration and testing methods. It appears that a high quality 750 watt power supply would be just about right.
Corsair and Seasonic are two brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Some of the newer models come with a 7 year warranty (in the USA).
I hate to say this, but while more overhead capability would be desireable, the original question regarding the XFX 650W's suitability is still "YES".
Regardless, take a look at the ratings for each of the recommended PSUs before you buy. Both the Silverstone and the Corsair (by a huge margin) have much better ratings than the OCZ.
What is your budget? That will drive your decision greatly. If money were no object (can anyone ever really say that?), I would recommend a Seasonic (as JohnnyLucky indicated), they are truly excellent PSUs.