Most people don't really understand what they mean when they say bottleneck. Any quad core processor that's reasonably OC'ed (like 3.7GHz+) is going to be just fine and won't hold you back in most situations. There are some games that will get better performance with the best processors, but a 2500k will put you right near the top of the performance heap when OC'ed to 4.5 GHz. Should be the center of a great build. Cheers!
A bottleneck occurs when something in your system is more/less than the system needs, whether that is a PSU, Motherboard, GPU, CPU, Case, etc. With a stock Core i5 2500k, you should be fine. A 2500k OCed to 4.5Ghz will be MORE than enough along with everything else. Build looks good! Have fun with it!
For educational purposes. Bottlenecking is where you have one component (typically the CPU when you hear people discuss it) is a significantly lower performance part than what's in other parts of the system. For example, if you have a slow dual core processor in a system with an extremely high end graphics card, you will get limited performance in most games because your CPU can't keep up with the rest of the system.
That being said, as I mentioned you don't need the latest processor to build a balanced system. Just a relatively modern quad core one with a good OC.
Feel free to post again when you finish your build, or hit up the forums with any other questions. A lot of smart folks here!