I have a Core i5 - 3470 - 3.20GHz and i am able to play super mario galaxy 1 and 2 just fine, even with upping the settings to HD.
So i would assume any CPU that is same or better than mine would be sufficient enough to play.
http://cpuboss.com/cpus/Intel-Core-i5-750-vs-Intel-Core-i5-3470
Depending on your motherboard you could hopefully just upgrade the CPU, save everything else, you have enough ram and a good enough GPU to use.
And PS2 games can be more or less demanding, i think it had more to due with the emulator too, i feel dolphin is more efficient at what it does than any current ps2 emulator.
So i would assume any CPU that is same or better than mine would be sufficient enough to play.
http://cpuboss.com/cpus/Intel-Core-i5-750-vs-Intel-Core-i5-3470
Depending on your motherboard you could hopefully just upgrade the CPU, save everything else, you have enough ram and a good enough GPU to use.
And PS2 games can be more or less demanding, i think it had more to due with the emulator too, i feel dolphin is more efficient at what it does than any current ps2 emulator.