Hey would a hd 7870 bottleneck an i3

At that resolution, the cpu would be the bottleneck. Which i3 are you getting? I think any i3 with an 7870 or 660 would be great.

Edit: I just saw your sig. The i3 2120 will not bottleneck a 7870 or 660. You should be good.
 
Both yes and no.

Some games are optimized to use 4-cores or more, those will bottleneck. Actually I heard on NCIXtechtips that if you run a dual-core CPU in Battlefield 3, some of the men aren't even in the campaign!!

In others as shown in the video below, there won't be any significant difference.

In the future you might have problems because more and more games are getting optimized to use more cores.

http://www.youtube.com/watch?v=I4PDoy-mi0A Here is the video. :)

So if you can, get a i5 that would be the best choice. You don't need a i5-3570k, just go with non-k version or get a i5-3470.
 
I guess what amuffin is trying to say is why are you trying to upgrade from a 6950 as it should meet your current requirements already. If you are having issues with it, then it may be time to upgrade (depending on what your issues are, this may be the CPU or GPU)...
 
well i changed form a amd phemon x 4 840 and gtx 550ti because i was not happy with the performce and the i3 is good but some games like battlefiled 3 and gta 4 use quad cores and i was planing to get an i5 but i went and got an i3 but i would still like to i5
 
Yeah, GTA IV doesn't run that great on any hardware configuration. The game needs more than 1GB of video RAM, and yet by default won't use more than 1GB due to some stupid programming decision. For optimal performance in GTA IV make sure you have at least patch 1.0.4.0, also turn down your draw distance and shadows, get your video memory usage down below 1GB, then it should be playable. The game will still dip down to around 30FPS in denser areas, but there is nothing you can really do about that. GTA IV was just that bad of a port.