Re: E6300/6400 or E6600?
Most E6600s I've seen will overclock to at least 3.4gHz. I haven't seen as many 6400s go that high, although I have seen a # of them that will.
Clock for clock the 6600s are a little faster because of the extra cache.
i7-2700k @ 5.0 GHz
Nvidia GeForce 570 2.5GB Tri-SLI
Asus P67 WS Revolution (Tri-SLI)
OCZ Vertex SSD x 4 (Raid 5)
G.Skill 8GB DDR3 @ 1600MHz
PC Power & Cooling 950W PSU