Gtx 650ti will bottleneck core 2 quad @ 2.66

no it will not bottleneck, what is your PSU brand?

No there will no bottleneck with core 2 quad.are you buying new one core 2 quad as at that price you can get new modern cpu.

Actually, core 2 quad will bottleneck the 650ti but not by much I suppose. OC the cpu will minimize it though

I have a Q8300 at 3.1GHz before and ran it with a GTX460. Games like Assassin's Creed Revelation, Dirt 2 & 3, Starcraft II and the Sims 3 all ran at 40fps or so on average. Minimums are borderline 30fps on most games (AC Revelation 20fps, Dirt 2 & 3 above 40fps). Switching to a 3570K showed huge improvements. Most games run at average 60fps and minimums are around 40fps.

good but will i be able to run gta v on it?

GTAV isn't out yet. You could probably run it on medium, take this with a huge grain of salt.