I'm thinking about sli-ing my current EVGA GTX 660 sig2 with another 660. But I'm a little scared to do it because I'm really worried about it being bottle-necked by my semi-low-end CPU, I've seen the GTX 680 not be bottle-necked by an i3-3220 which is at about the same performance as the FX-6100. I'm also thinking about upgrading it to either the FX-8230 or FX-8350, is there a large performance diffference between them? And will those CPUs bottle-neck GTX 660s?