1920x1080p with HDMI cable. Will There Be Any Noticeable Bottleneck. Metro 2033, Battlefield 3, Saint Row The Third Mostly Games Like That. 23 in 1920x1080 price and just bottleneck really. dont want to OC CPU
Moving to i5 would mean an entire platform change and 1155 is a dead socket. I would rather grab a 6300 and OC that to 4 Ghz and wait for Steamroller which is supposed to fix the fetch/decode bottleneck in Vishera. At 4 ghz the 6300 can match a i5 3570 stock while costing about $90 chepaer and not requiring any change in platform. The i5 is better CPU if both are overclocked but both will give you 45+ fps in most situations. The 4100 will be fine with the 7850 OC and won't bottleneck at all. With a 7870 there will be some bottle necking involved in BF3 at stock clocks unless you play at Ultra in which case the load gets shifted back to the GPU.
I would expect the 7850 OC to hit about 49~50 fps.
Bottleneck is also a misused term at times. E.g. CPU can push 60fps, GPU at High settings can push 70fps. That is CPU bottle necking the GPU. But turn the graphics up to ultra and CPU still pushes about 60fps and the GPU can only push 70fps. No more bottleneck. This is a very rough description. I would only worry about the CPU or GPU being able to push playable frame rates ~45fps+ since you can always move the better performing parts into a newer build.
You need to do some overclocking on the 4100 no matter which card you get in order to get 45fps+ all the time in the outdoors BF3 64 player maps. The 4100 stock is good for most games but really needs the extra speed in some games.
You can grab a 6300 and OC that since it will give you more frames at stock and Overclocked.
If you do grab the 7870 you should grab the 6300 and wait for steamroller to upgrade.
Intel has me worried about the upgrade path due to Broadwell maybe having the CPU soldered on the motherboard.
For best performance in BF3 64 player maps
7850 OC - 4100 OC or 6300 stock
7870 - 6300 stock or OC
What you should do is grab the GPU based on the fps you want since the GPU is usually the limiting factor. The 7850 OC is more for ultra with no MSAA @1080p for 60+ fps avg. The 7870 is for 4xMSAA @1080p for 60+fps avg. If you have the money, get the 7870 but if not the 7850 OC will do fine too.
If you get lower than expected fps, try overlclocking the 4100 and see how that goes. Might want to consider a 6300 about then if the fps is still below your requirements. A 6300 OC should have no problems pushing the 7870 to the max.