You would need a new M/B. A 7770 will not bottleneck your cpu btw. However if I was going to spend some money to upgrade right now I would go here: http://www.newegg.com/Product/Product.aspx?Item=N82E16819103727
Then put the rest of the money into a GPU. Unless your budget is under $200. Then just pick up an HD7850,7870 or GTX660,Ti if you can afford that much.