To the op the g2010 will bottleneck the 7770 in highly threaded games. Codemaster games the i3 destroys the pentium line cpus as there games need 4 threads. Get the i3 at least.
It sounds the OP already owns G2010 and HD 7770.
True, i3 destroys the Pentiums in those racing games (and most games), but it isn't required and his GPU would top out earlier. The G2010 can max out 1920x1080 (Ultra preset with 8x MSAA) in F1 2012 and the DiRT series, rarely ever dropping below 40 fps. Can't speak for GRID 2, but in their other series you'll see GPU scaling with his HD 7770 (as you increase resolutions with Ultra). Actually, an overclocked 7770 and G2010 would just about be a perfect match at 1920x1080. The balance shifts (GPU scaling fades) somewhere between stock HD 7770 and HD 7850.