Need to know this before i get the second 560ti!
Let me explain something, bottleneck effect, is when lets say you have a game, lets it needs Dual 3 Ghz CPU and atleast GTX 560 GPU or higher, to run at 60 FPS constantly.
If you have a CPU, like dual 2,5GHz, you wont get the 60 FPS, because your CPU is running at lower clock rate, so you will get lower FPS. So your CPU is bottlenecking your GPU on that game, it can also be the other way around, a weaker GPU like 540 will also handycap your system for that game.
*There are other factors to take into account, this is just to illustrate a point, Clock Rate is not the only thing to measure CPU and GPU performance by!
The trick is to balance out CPU and GPU, You dont want an I7 3770k with some low end GPU, and the other way around.
It comes down to what you do with your computer, different games use both CPU and GPU differently, some put a heavy load on your GPU, by having high textures, others need a good CPU to do different calculations.
You could gain a lot of FPS in some games, well, you will gain some in all games i suppose, because you get more DDR5. Especially games what use High textures, like skyrim with HD texture packs, it wont need much CPU, but i just eats your video card.
anyway, hope this helps you a bit, if you have some specific applications or games, just post them and somebody can propably give you a more accurate answer.
Yes it will, plain and simple...
A little bit.
I would say slightly depending on the game