"Bottlenecking" can be highly over-rated. A good quad core processor won't keep the graphics subsystem waiting long enough for you to even notice in normal gaming. You're usually only talking single digit FPS differences.
That being said, your Athlon II X4 630 is only in the Intel Core 2 Duo catagory as far as speed. So you will experience some loss of the card's true capability. But unless you are willing to upgrade your processor, I'd say go for it anyway. It'll be a major
improvement over the HD 6570.http://www.tomshardware.com/reviews/gaming-cpu-review-overclock,3106-5.html