No, an i5 2500k won't bottleneck that system. While the GTX 680 is quite powerful, the i5 2500K is as well. It offers all the real-world performance of the highest end processors, without the markup and special use case features. (HTT, 6 Cores, etc.) Sure, there might be situations where it will be a bottleneck, but those would be in low-detail situations or settings where the 680 is pushing out more than 100+ FPS. Really, for gaming, the 2500K offers excellent price/performance.