So I'm getting a i5-2500k and a GTX 670FTW+. Since only the i7 can utilize the PCI-E 3.0 how badly will my i5 bottleneck the 670? I didn't want an i7 because of the HT and it's effect on games, considering I have a gaming rig. The mobo I'm getting is an ASRock Extreme4 Z77 if it makes a difference. Probably not.
Well, first of all, that's not true. Any Ivy Bridge i5 or i7 can. The 2500K is Sandy Bridge, of course, so it can't, but neither can a Sandy Bridge i7 (2600K/2700K).
So, it just needs to be an Ivy i5, like the 3570K.
Second, no it doesn't really matter. There is some difference, but it's around 1%.
Having said all of that, just get an i5 3570K. You'll have PCIe 3.0 and not have to deal with HT either (even though I'm pretty sure most games that had trouble with HT are patched or probably will be).