With the Q9650, you should be able to play GTA 5 at a way better performance with extra 2 cores. The most powerful(and latest) GTX series graphics card that does not need any external power would be the 1050 Ti. You should be able play at high/very high settings at least above 60 FPS.
The Pentium E5500 is extremely weak for this game and will significantly bottleneck the 1050 Ti.