Your fine there should be no issues.
the CPU is plenty powerful enough for that GPU and power wise, well even if its got mice running on wheels inside it a 750w PSU would need to be broken not to run that set up.
The i3-2120 won't bottle neck many graphics cards in gaming today.
If you look at the Tom's Hardware $500 build for June, you'll see they paired a G630 with a 560ti.
Of course that did seem to bottleneck in a few games and is an incredibly unbalanced build,
it gives you an idea how far a low end Sandy Bridge CPU can go even while paired with a much more expensive GPU (6850/560ti)