you want to keep the same processor but change the mb and RAM?
This is nuts and a waste of money. It would not make your computer run faster , nor produce higher frame rates . There is no performance advantage in using DDR3 .
There is a small gain to be had from upgrading processor, motherboard and RAM and graphics card to the latest Intel or AMD hardware , but before you spend the money it would be helpful if you told us what resolution you play at and what your operating system is