If you haven't bought it yet, why aren't you getting the i5-3570k? It's considerably faster, cooler, and newer tech, for about $10 more.
The 2500k doesn't even support PCIe 3.0. (Not that it matters - there will be about a 2fps difference between 2.0 and 3.0 for you.)
I havent settled on a CPU yet. Odd that you bring that up btw because I was just looking at newegg and the I5-3570k is actually cheaper then the 2500k right now because they have a deal going on. So I will probably go with the 3570k.. I'm still stuck on what motherboard to get though.