No, it shouldn't be a bottleneck at all unless a particular game is just horrendously optimized, in which case newer processors are likely to be bottlenecks as well.
I'm CPU limited at times on a 4770k @4.6ghz in Borderlands 2, dropping my single 770 below 70% load, just from randomly playing singleplayer. A whole lot of games hit CPU limits especially when you have a lot of GPU power, because you're demanding nearly twice as much FPS from the CPU when you drop in another card.
I upgraded from a 950@4ghz to firstname.lastname@example.org on single GPU, and it's kinda a massive deal for a lot of games, don't make it out to be nothing when you have twice as much graphical power so you're demanding almost twice as high FPS from the CPU
I could name quite a lot of modern games (just ones i had interest in) that hit CPU limits on one high end GPU and haswell, but for two gpu's and a CPU a large gap behind in singlethreaded performance, it's easier
Don't take my word for it, grab a second screen and throw up task manager, msi afterburner, watch individual CPU cores and GPU usage in various games and situationsEdited by Cyro999 - 9/19/13 at 4:59am