You mean will the Pentium g3220 bottleneck the GTX 760? It will in some games such as Battlefield 4, Crysis 3, and Pretty much any of Ubisoft's new games..
Oh, if that so, maybe you will be the few of those people who will have a set up like that and maybe you can try it by yourself. Afterall G3220 is not a bad CPU.
It's at a price where it really isn't worth getting a slower card and it's not worth the added cost to get one that's a little better. You will see a performance increase with this graphics card even with your dual core Pentium but the card won't reach its max potential until you also upgrade your CPU. It's the best deal I could find. upgrading the GPU now is the best move you can make with what's on the market today... But there's another option... You could upgrade your CPU now to a Core i5 and then wait for the GTX 960, 960 ti, or 965 ti. Those GPU's could launch by the end of the month.
if your gonna play games go with a fx 8320 its cheaper and runs better on multi threaded games the i5 4430 only beats it in the single threaded performance