The thing with bottle-necking is that it can happen to both components: CPU and GPU. in Layman's terms: If one component processes information at a faster rate than the other, then that would create a bottle-neck.
The RAM of the Video Card serves as the buffer memory that would keep the information to process until the processing cores on the Vid card are ready for it. So, the RAM is not that big of an issue when you speak of bottle-necking. You need to look at the clock speeds of the memory, core, etc., along with, the amount of processing cores and how the data is transfered to the CPU.
But, you should have no issue with bottle-necking with the i5-760 with any of the current vid cards. The reason is too technical lol, unless of course, you want to hear it.
