THe 650Ti boost is doable on your current power supply but i would recommend at some point upgrade it to a better quality.
Stick to brands such as: Antec, Corsair(AX,HX or TX series only), Seasonic or XFX
What is your planned gpu upgrade?
What is your current power supply? Brand and model? How many amps on the 12V rails?
i3 is still ok for now. They still capable of delivering performance.
THe 650Ti boost is doable on your current power supply but i would recommend at some point upgrade it to a better quality.
Stick to brands such as: Antec, Corsair(AX,HX or TX series only), Seasonic or XFX