I'm not a fan of buying the newest, bestest, most expensivest stuff, generally. In this case, if you're mainly interested in gaming, the i5-2500 is very nearly as good, and a ton cheaper. The i7 mainly excels in 3d editing and such. I paid $85 for my i5 (after bundle and black Friday discounts) and I'm quite happy with it.
Since you're getting a liquid cooler, I guess you'll be overclocking it, and the i7 does have more overhead for that sort of thing. Still, people are easily getting their i5's up to 4700ghz or so just with air cooling.
And out of curiosity, what makes that $315 mobo any better than all the other z68 chipset boards?